Adding Concrete Syntax to a Prolog-Based Program Synthesis System

NASA Technical Reports Server (NTRS)

Fischer, Bernd; Visser, Eelco

2004-01-01

Program generation and transformation systems work on two language levels, the object-level (i e., the language of the manipulated programs), and the meta-level (i.e., the implementation language of the system itself). The meta-level representations of object-level program fragments are usually built in an essentially syntax-free fashion using the operations provided by the meta-language. However, syntax matters and a large conceptual distance between the two languages makes it difficult to maintain and extend such systems. Here we describe how an existing Prolog-based system can gradually be retrofitted with concrete object-level syntax, thus shrinking this distance.

Real-time interactive 3D manipulation of particles viewed in two orthogonal observation planes.

PubMed

Perch-Nielsen, Ivan; Rodrigo, Peter; Glückstad, Jesper

2005-04-18

The generalized phase contrast (GPC) method has been applied to transform a single TEM00 beam into a manifold of counterpropagating-beam traps capable of real-time interactive manipulation of multiple microparticles in three dimensions (3D). This paper reports on the use of low numerical aperture (NA), non-immersion, objective lenses in an implementation of the GPC-based 3D trapping system. Contrary to high-NA based optical tweezers, the GPC trapping system demonstrated here operates with long working distance (>10 mm), and offers a wider manipulation region and a larger field of view for imaging through each of the two opposing objective lenses. As a consequence of the large working distance, simultaneous monitoring of the trapped particles in a second orthogonal observation plane is demonstrated.

Refocusing distance of a standard plenoptic camera.

PubMed

Hahne, Christopher; Aggoun, Amar; Velisavljevic, Vladan; Fiebig, Susanne; Pesch, Matthias

2016-09-19

Recent developments in computational photography enabled variation of the optical focus of a plenoptic camera after image exposure, also known as refocusing. Existing ray models in the field simplify the camera's complexity for the purpose of image and depth map enhancement, but fail to satisfyingly predict the distance to which a photograph is refocused. By treating a pair of light rays as a system of linear functions, it will be shown in this paper that its solution yields an intersection indicating the distance to a refocused object plane. Experimental work is conducted with different lenses and focus settings while comparing distance estimates with a stack of refocused photographs for which a blur metric has been devised. Quantitative assessments over a 24 m distance range suggest that predictions deviate by less than 0.35 % in comparison to an optical design software. The proposed refocusing estimator assists in predicting object distances just as in the prototyping stage of plenoptic cameras and will be an essential feature in applications demanding high precision in synthetic focus or where depth map recovery is done by analyzing a stack of refocused photographs.

Instruments for Imaging from Far to Near

NASA Technical Reports Server (NTRS)

Mungas, Greg; Boynton, John; Sepulveda, Cesar

2009-01-01

The acronym CHAMP (signifying camera, hand lens, and microscope ) denotes any of several proposed optoelectronic instruments that would be capable of color imaging at working distances that could be varied continuously through a range from infinity down to several millimeters. As in any optical instrument, the magnification, depth of field, and spatial resolution would vary with the working distance. For example, in one CHAMP version, at a working distance of 2.5 m, the instrument would function as an electronic camera with a magnification of 1/100, whereas at a working distance of 7 mm, the instrument would function as a microscope/electronic camera with a magnification of 4.4. Moreover, as described below, when operating at or near the shortest-working-distance/highest-magnification combination, a CHAMP could be made to perform one or more spectral imaging functions. CHAMPs were originally intended to be used in robotic geological exploration of the Moon and Mars. The CHAMP concept also has potential for diverse terrestrial applications that could include remotely controlled or robotic geological exploration, prospecting, field microbiology, environmental surveying, and assembly- line inspection. A CHAMP (see figure) would include two lens cells: (1) a distal cell corresponding to the objective lens assembly of a conventional telescope or microscope and (2) a proximal cell that would contain the focusing camera lens assembly and the camera electronic image-detector chip, which would be of the active-pixel-sensor (APS) type. The distal lens cell would face outward from a housing, while the proximal lens cell would lie in a clean environment inside the housing. The proximal lens cell would contain a beam splitter that would enable simultaneous use of the imaging optics (that is, proximal and distal lens assemblies) for imaging and illumination of the field of view. The APS chip would be mounted on a focal plane on a side face of the beam splitter, while light for illuminating the field of view would enter the imaging optics via the end face of the beam splitter. The proximal lens cell would be mounted on a sled that could be translated along the optical axis for focus adjustment. The position of the CHAMP would initially be chosen at the desired working distance of the distal lens from (corresponding to an approximate desired magnification of) an object to be examined. During subsequent operation, the working distance would ordinarily remain fixed at the chosen value and the position of the proximal lens cell within the instrument would be adjusted for focus as needed.

Crawling and walking infants encounter objects differently in a multi-target environment.

PubMed

Dosso, Jill A; Boudreau, J Paul

2014-10-01

From birth, infants move their bodies in order to obtain information and stimulation from their environment. Exploratory movements are important for the development of an infant's understanding of the world and are well established as being key to cognitive advances. Newly acquired motor skills increase the potential actions available to the infant. However, the way that infants employ potential actions in environments with multiple potential targets is undescribed. The current work investigated the target object selections of infants across a range of self-produced locomotor experience (11- to 14-month-old crawlers and walkers). Infants repeatedly accessed objects among pairs of objects differing in both distance and preference status, some requiring locomotion. Overall, their object actions were found to be sensitive to object preference status; however, the role of object distance in shaping object encounters was moderated by movement status. Crawlers' actions appeared opportunistic and were biased towards nearby objects while walkers' actions appeared intentional and were independent of object position. Moreover, walkers' movements favoured preferred objects more strongly for children with higher levels of self-produced locomotion experience. The multi-target experimental situation used in this work parallels conditions faced by foraging organisms, and infants' behaviours were discussed with respect to optimal foraging theory. There is a complex interplay between infants' agency, locomotor experience, and environment in shaping their motor actions. Infants' movements, in turn, determine the information and experiences offered to infants by their micro-environment.

A Short-Range Distance Sensor with Exceptional Linearity

NASA Technical Reports Server (NTRS)

Simmons, Steven; Youngquist, Robert

2013-01-01

A sensor has been demonstrated that can measure distance over a total range of about 300 microns to an accuracy of about 0.1 nm (resolution of about 0.01 nm). This represents an exceptionally large dynamic range of operation - over 1,000,000. The sensor is optical in nature, and requires the attachment of a mirror to the object whose distance is being measured. This work resulted from actively developing a white light interferometric system to be used to measure the depths of defects in the Space Shuttle Orbiter windows. The concept was then applied to measuring distance. The concept later expanded to include spectrometer calibration. In summary, broadband (i.e., white) light is launched into a Michelson interferometer, one mirror of which is fixed and one of which is attached to the object whose distance is to be measured. The light emerging from the interferometer has traveled one of two distances: either the distance to the fixed mirror and back, or the distance to the moving mirror and back. These two light beams mix and produce an interference pattern where some wavelengths interfere constructively and some destructively. Sending this light into a spectrometer allows this interference pattern to be analyzed, yielding the net distance difference between the two paths. The unique feature of this distance sensor is its ability to measure accurately distance over a dynamic range of more than one million, the ratio of its range (about 300 microns) to its accuracy (about 0.1 nanometer). Such a large linear operating range is rare and arises here because both amplitude and phase-matching algorithms contribute to the performance. The sensor is limited by the need to attach a mirror of some kind to the object being tracked, and by the fairly small total range, but the exceptional dynamic range should make it of interest.

Photonic jet with ultralong working distance by hemispheric shell.

PubMed

Hengyu, Zhu; Zaichun, Chen; Chong, Chong Tow; Minghui, Hong

2015-03-09

Micro-particle assisted nano-imaging has proven its success in the past few years since it can magnify the nano-objects, especially the metallic objects, into an image then collected by a conventional microscope. Micro-shell, which is a novel design of micro-particle in the configuration of a hemisphere with a hollow core region, is proposed and optimized in this paper in order to obtain a long photonic jet far away from its flat surface, thus increasing its working distance. Its dependence on the configuration and refractive index is investigated numerically. A micro-shell with the outer and inner radii of 5 and 2.5 µm and the refractive index of 1.5 can focus the incident light of 400 nm wavelength 2.7 µm away from the micro-shell flat surface, although the photonic jet intensity decreases to 25.8% compared to the solid hemisphere. Meanwhile, the photonic jet length of the micro-shell under the incident light of 400 nm and 1000 nm wavelengths are 1.7 µm and 4.3 µm, respectively, because its hollow core region tends to reduce the angle variation of the Poynting vectors in the photonic jet. With the long working distance and long photonic jet, the micro-shell could be used to scan over a sample to obtain a large area image when coupled with a conventional microscope, which is especially useful for the samples with the rough surfaces.

Long working distance optical coherence tomography for pediatric imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Qian, Ruobing; Carrasco-Zevallos, Oscar; Vajzovic, Lejla; Gramatikov, Boris I.; Guyton, David L.; Toth, Cynthia A.; Izatt, Joseph A.

2016-03-01

Conventional optical coherence tomography (OCT) systems have working distances of about 25 mm, and require cooperative subjects to immobilize and fixate on a target. Handheld OCT probes have also been demonstrated for successful imaging of pre-term infants and neonates up to ~1 year old. However, no technology yet exists for OCT in young children due to their lack of attention and inherent fear of large objects close to their face. In this work, we demonstrate a prototype retinal swept-source OCT system with a long working distance (from the last optical element to the subject's eye) to facilitate pediatric imaging. To reduce the footprint and weight of the system compared to the conventional 4f scheme, a novel 2f scanning configuration was implemented to achieve a working distance of 348mm with a +/- 8° scanning angle prior to cornea. Employing two custom-designed lenses, the system design resolution was nearly diffraction limited throughout a -8D to +5D refractive corrections. A fixation target displayed on a LCD monitor and an iris camera were used to facilitate alignment and imaging. Our prototype was tested in consented adult subjects and has the potential to facilitate imaging of young children. With this apparatus, young children could potentially sit comfortably in caretaker's lap while viewing entertainment on the fixation screen designed to direct their gaze into the imaging apparatus.

First year physics practicals in distance education in South Africa

NASA Astrophysics Data System (ADS)

Cilliers, Johanna Albertha

Although the merits of practical work in physics is often questioned, it remains part of physics curricula word- wide. In distance education the incorporation of practical work into the curriculum is considerably complicated by the unique logistics of the setting and the high cost involved. The research reported in this thesis emanated from the need to improve the practical work module for first year physics at the University of South Africa, one of the largest distance education universities in the world. Specifically, the home-based component which, up to the commencement of the research had been entirely text-based, needed to be addressed. To this end it was necessary to identify a valid and attainable set of objectives and to determine the characteristics, abilities and needs of the students in the target group. A survey polling the viewpoints of South African physics lecturers and students about the objectives of practical work was conducted and an extensive student profile comprising a biographic, cognitive and affective component was compiled. Biographically, the target group is unique in the sense that it consists mainly of adult learners, a large percentage of whom study in a second language. The cognitive component of the profile covered aptitude, proficiency in English, mathematics and the integrated science process skills and level of cognitive development, all of which were investigated for possible influence on performance in practical work. On an affective level, students displayed a very positive attitude towards practical work, seated mainly in their need for concrete exploration of the theory. A practical work module structured around an experiential learning cycle adapted to the distance education environment was subsequently designed. The study material developed for the module comprised an interactive study guide on data processing and experimental procedure, a home experiment kit with accompanying workbook and a laboratory manual. From the pilot study forming part of the development process, it was found that students performed significantly better in an assignment based on home- experimentation than in any of the pen-and-paper assignments preceding it. Based on the results of the pilot study, a full home experiment kit was designed, evaluated, refined and implemented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Junhwan; Hwang, Sungui; Park, Kyihwan, E-mail: khpark@gist.ac.kr

To utilize a time-of-flight-based laser scanner as a distance measurement sensor, the measurable distance and accuracy are the most important performance parameters to consider. For these purposes, the optical system and electronic signal processing of the laser scanner should be optimally designed in order to reduce a distance error caused by the optical crosstalk and wide dynamic range input. Optical system design for removing optical crosstalk problem is proposed in this work. Intensity control is also considered to solve the problem of a phase-shift variation in the signal processing circuit caused by object reflectivity. The experimental results for optical systemmore » and signal processing design are performed using 3D measurements.« less

Confocal Imaging of the Embryonic Heart: How Deep?

NASA Astrophysics Data System (ADS)

Miller, Christine E.; Thompson, Robert P.; Bigelow, Michael R.; Gittinger, George; Trusk, Thomas C.; Sedmera, David

2005-06-01

Confocal microscopy allows for optical sectioning of tissues, thus obviating the need for physical sectioning and subsequent registration to obtain a three-dimensional representation of tissue architecture. However, practicalities such as tissue opacity, light penetration, and detector sensitivity have usually limited the available depth of imaging to 200 [mu]m. With the emergence of newer, more powerful systems, we attempted to push these limits to those dictated by the working distance of the objective. We used whole-mount immunohistochemical staining followed by clearing with benzyl alcohol-benzyl benzoate (BABB) to visualize three-dimensional myocardial architecture. Confocal imaging of entire chick embryonic hearts up to a depth of 1.5 mm with voxel dimensions of 3 [mu]m was achieved with a 10× dry objective. For the purpose of screening for congenital heart defects, we used endocardial painting with fluorescently labeled poly-L-lysine and imaged BABB-cleared hearts with a 5× objective up to a depth of 2 mm. Two-photon imaging of whole-mount specimens stained with Hoechst nuclear dye produced clear images all the way through stage 29 hearts without significant signal attenuation. Thus, currently available systems allow confocal imaging of fixed samples to previously unattainable depths, the current limiting factors being objective working distance, antibody penetration, specimen autofluorescence, and incomplete clearing.

Field Testing of Utility Robots for Lunar Surface Operations

NASA Technical Reports Server (NTRS)

Fong, Terrence; Bualat, Maria; Deans, Matt; Allan, Mark; Bouyssounouse, Xavier; Broxton, Michael; Edwards, Laurence; Lee, Pascal; Lee, Susan Y.; Lees, David;

Aerial vehicles collision avoidance using monocular vision

NASA Astrophysics Data System (ADS)

Balashov, Oleg; Muraviev, Vadim; Strotov, Valery

2016-10-01

In this paper image-based collision avoidance algorithm that provides detection of nearby aircraft and distance estimation is presented. The approach requires a vision system with a single moving camera and additional information about carrier's speed and orientation from onboard sensors. The main idea is to create a multi-step approach based on a preliminary detection, regions of interest (ROI) selection, contour segmentation, object matching and localization. The proposed algorithm is able to detect small targets but unlike many other approaches is designed to work with large-scale objects as well. To localize aerial vehicle position the system of equations relating object coordinates in space and observed image is solved. The system solution gives the current position and speed of the detected object in space. Using this information distance and time to collision can be estimated. Experimental research on real video sequences and modeled data is performed. Video database contained different types of aerial vehicles: aircrafts, helicopters, and UAVs. The presented algorithm is able to detect aerial vehicles from several kilometers under regular daylight conditions.

Optical design and evaluation of a 4 mm cost-effective ultra-high-definition arthroscope.

PubMed

Cheng, Dewen; Wang, Yongtian; Yu, Lu; Liu, Xiaohua

2014-08-01

High definition and magnification rigid endoscope plays an important role in modern minimally invasive medical surgery and diagnosis. In this paper, we present the design and evaluation methods of a high definition rigid endoscope, specifically an arthroscope, with a large depth of field (DOF). The incident heights and exit angles of the sampled rays on the relay lens are controlled during the optimization process to ensure an effective field view (70°) and a normal ray path within the limited lens diameter of 2.7 mm. The lens is set up as a multi-configuration system with two extreme and one middle object distances to cover a large DOF. As a result, an entrance pupil of 0.3 mm is achieved for the first time, to bring the theoretical resolution to 23.1 lps/mm in the object space at a working distance of 20 mm, with the wavelength of 0.532 um. The modulation transfer function (MTF) curves approach diffraction limit, and the values are all higher than 0.3 at 160 line pairs/mm (lps/mm) in the image space. Meanwhile, stray light caused by total internal reflection on the inner wall of the rod lenses and the objective lens is eliminated. The measured resolution in the object space at a 20 mm working distance is 22.3 lps/mm, and test results show that other performance characteristics also fulfill design requirements. The relay lenses are designed with only one type of the spacer and two types of lenses to greatly reduce the fabrication and assembly cost. The design method has important research and application values for lens systems used in modern minimally invasive medical surgery and industrial non-destructive testing area.

Learning object-to-class kernels for scene classification.

PubMed

Zhang, Lei; Zhen, Xiantong; Shao, Ling

2014-08-01

High-level image representations have drawn increasing attention in visual recognition, e.g., scene classification, since the invention of the object bank. The object bank represents an image as a response map of a large number of pretrained object detectors and has achieved superior performance for visual recognition. In this paper, based on the object bank representation, we propose the object-to-class (O2C) distances to model scene images. In particular, four variants of O2C distances are presented, and with the O2C distances, we can represent the images using the object bank by lower-dimensional but more discriminative spaces, called distance spaces, which are spanned by the O2C distances. Due to the explicit computation of O2C distances based on the object bank, the obtained representations can possess more semantic meanings. To combine the discriminant ability of the O2C distances to all scene classes, we further propose to kernalize the distance representation for the final classification. We have conducted extensive experiments on four benchmark data sets, UIUC-Sports, Scene-15, MIT Indoor, and Caltech-101, which demonstrate that the proposed approaches can significantly improve the original object bank approach and achieve the state-of-the-art performance.

Exploring New Geometric Worlds

ERIC Educational Resources Information Center

Nirode, Wayne

2015-01-01

When students work with a non-Euclidean distance formula, geometric objects such as circles and segment bisectors can look very different from their Euclidean counterparts. Students and even teachers can experience the thrill of creative discovery when investigating these differences among geometric worlds. In this article, the author describes a…

An evaluation of lithographed forest stereograms.

Treesearch

David A. Bernstein

1961-01-01

Aerial photo stereograms are valuable for showing neophyte photo interpreters the stereoscopic appearance of common objects and conditions. They are also useful for instruction in measuring heights, horizontal distances, and angles on photos. Collections of stereograms of known conditions are worthwhile reference material for interpretation work in unknown areas.

A position paper of the EFLM Committee on Education and Training and Working Group on Distance Education Programmes/E-Learning: developing an e-learning platform for the education of stakeholders in laboratory medicine.

PubMed

Gruson, Damien; Faure, Gilbert; Gouget, Bernard; Haliassos, Alexandre; Kisikuchin, Darya; Reguengo, Henrique; Topic, Elizabeta; Blaton, Victor

2013-04-01

The progress of information and communication technologies has strongly influenced changes in healthcare and laboratory medicine. E-learning, the learning or teaching through electronic means, contributes to the effective knowledge translation in medicine and healthcare, which is an essential element of a modern healthcare system and for the improvement of patient care. E-learning also represents a great vector for the transfer knowledge into laboratory practice, stimulate multidisciplinary interactions, enhance continuing professional development and promote laboratory medicine. The European Federation of Laboratory Medicine (EFLM) has initiated a distance learning program and the development of a collaborative network for e-learning. The EFLM dedicated working group encourages the organization of distance education programs and e-learning courses as well as critically evaluate information from courses, lectures and documents including electronic learning tools. The objectives of the present paper are to provide some specifications for distance learning and be compatible with laboratory medicine practices.

A Recursive Partitioning Method for the Prediction of Preference Rankings Based Upon Kemeny Distances.

PubMed

D'Ambrosio, Antonio; Heiser, Willem J

2016-09-01

Preference rankings usually depend on the characteristics of both the individuals judging a set of objects and the objects being judged. This topic has been handled in the literature with log-linear representations of the generalized Bradley-Terry model and, recently, with distance-based tree models for rankings. A limitation of these approaches is that they only work with full rankings or with a pre-specified pattern governing the presence of ties, and/or they are based on quite strict distributional assumptions. To overcome these limitations, we propose a new prediction tree method for ranking data that is totally distribution-free. It combines Kemeny's axiomatic approach to define a unique distance between rankings with the CART approach to find a stable prediction tree. Furthermore, our method is not limited by any particular design of the pattern of ties. The method is evaluated in an extensive full-factorial Monte Carlo study with a new simulation design.

Are Perceived and Objective Distances to Fresh Food and Physical Activity Resources Associated with Cardiometabolic Risk?

PubMed

Baldock, Katherine L; Paquet, Catherine; Howard, Natasha J; Coffee, Neil T; Taylor, Anne W; Daniel, Mark

2018-01-29

Perceived and objective measures of neighbourhood features have shown limited correspondence. Few studies have examined whether discordance between objective measures and individual perceptions of neighbourhood environments relates to individual health. Individuals with mismatched perceptions may benefit from initiatives to improve understandings of resource availability. This study utilised data from n = 1491 adult participants in a biomedical cohort to evaluate cross-sectional associations between measures of access (perceived, objective, and perceived-objective mismatch) to fruit and vegetable retailers (FVR) and public open space (POS), and clinically-measured metabolic syndrome and its component risk factors: central obesity, dyslipidaemia, hypertension and pre-diabetes/diabetes. Access measures included perceived distances from home to the nearest FVR and POS, corresponding objectively-assessed road network distances, and the discordance between perceived and objective distances (overestimated (i.e., mismatched) distances versus matched perceived-objective distances). Individual and neighbourhood measures were spatially joined using a geographic information system. Associations were evaluated using multilevel logistic regression, accounting for individual and area-level covariates. Hypertension was positively associated with perceived distances to FVR (odds ratio (OR) = 1.14, 95% confidence interval (CI) = 1.02, 1.28) and POS (OR = 1.19, 95% CI = 1.05, 1.34), after accounting for covariates and objective distances. Hypertension was positively associated with overestimating distances to FVR (OR = 1.36, 95% CI = 1.02, 1.80). Overestimating distances to POS was positively associated with both hypertension (OR = 1.42, 95% CI = 1.11, 1.83) and dyslipidaemia (OR = 1.25, 95% CI = 1.00, 1.57). Results provide new evidence for specific associations between perceived and overestimated distances from home to nearby resources and cardiometabolic risk factors.

Cognitive domains in the dog: independence of working memory from object learning, selective attention, and motor learning.

PubMed

Zanghi, Brian M; Araujo, Joseph; Milgram, Norton W

2015-05-01

Cognition in dogs, like in humans, is not a unitary process. Some functions, such as simple discrimination learning, are relatively insensitive to age; others, such as visuospatial learning can provide behavioral biomarkers of age. The present experiment sought to further establish the relationship between various cognitive domains, namely visuospatial memory, object discrimination learning (ODL), and selective attention (SA). In addition, we also set up a task to assess motor learning (ML). Thirty-six beagles (9-16 years) performed a variable delay non-matching to position (vDNMP) task using two objects with 20- and 90-s delay and were divided into three groups based on a combined score (HMP = 88-93 % accuracy [N = 12]; MMP = 79-86 % accuracy [N = 12]; LMP = 61-78 % accuracy [N = 12]). Variable object oddity task was used to measure ODL (correct or incorrect object) and SA (0-3 incorrect distractor objects with same [SA-same] or different [SA-diff] correct object as ODL). ML involved reaching various distances (0-15 cm). Age did not differ between memory groups (mean 11.6 years). ODL (ANOVA P = 0.43), or SA-same and SA-different (ANOVA P = 0.96), performance did not differ between the three vDNMP groups, although mean errors during ODL was numerically higher for LMP dogs. Errors increased (P < 0.001) for all dogs with increasing number of distractor objects during both SA tasks. vDNMP groups remained different (ANOVA P < 0.001) when re-tested with vDNMP task 42 days later. Maximum ML distance did not differ between vDNMP groups (ANOVA P = 0.96). Impaired short-term memory performance in aged dogs does not appear to predict performance of cognitive domains associated with object learning, SA, or maximum ML distance.

Sensory prediction on a whiskered robot: a tactile analogy to “optical flow”

PubMed Central

Schroeder, Christopher L.; Hartmann, Mitra J. Z.

2012-01-01

When an animal moves an array of sensors (e.g., the hand, the eye) through the environment, spatial and temporal gradients of sensory data are related by the velocity of the moving sensory array. In vision, the relationship between spatial and temporal brightness gradients is quantified in the “optical flow” equation. In the present work, we suggest an analog to optical flow for the rodent vibrissal (whisker) array, in which the perceptual intensity that “flows” over the array is bending moment. Changes in bending moment are directly related to radial object distance, defined as the distance between the base of a whisker and the point of contact with the object. Using both simulations and a 1×5 array (row) of artificial whiskers, we demonstrate that local object curvature can be estimated based on differences in radial distance across the array. We then develop two algorithms, both based on tactile flow, to predict the future contact points that will be obtained as the whisker array translates along the object. The translation of the robotic whisker array represents the rat's head velocity. The first algorithm uses a calculation of the local object slope, while the second uses a calculation of the local object curvature. Both algorithms successfully predict future contact points for simple surfaces. The algorithm based on curvature was found to more accurately predict future contact points as surfaces became more irregular. We quantify the inter-related effects of whisker spacing and the object's spatial frequencies, and examine the issues that arise in the presence of real-world noise, friction, and slip. PMID:23097641

Sensory prediction on a whiskered robot: a tactile analogy to "optical flow".

PubMed

Schroeder, Christopher L; Hartmann, Mitra J Z

2012-01-01

When an animal moves an array of sensors (e.g., the hand, the eye) through the environment, spatial and temporal gradients of sensory data are related by the velocity of the moving sensory array. In vision, the relationship between spatial and temporal brightness gradients is quantified in the "optical flow" equation. In the present work, we suggest an analog to optical flow for the rodent vibrissal (whisker) array, in which the perceptual intensity that "flows" over the array is bending moment. Changes in bending moment are directly related to radial object distance, defined as the distance between the base of a whisker and the point of contact with the object. Using both simulations and a 1×5 array (row) of artificial whiskers, we demonstrate that local object curvature can be estimated based on differences in radial distance across the array. We then develop two algorithms, both based on tactile flow, to predict the future contact points that will be obtained as the whisker array translates along the object. The translation of the robotic whisker array represents the rat's head velocity. The first algorithm uses a calculation of the local object slope, while the second uses a calculation of the local object curvature. Both algorithms successfully predict future contact points for simple surfaces. The algorithm based on curvature was found to more accurately predict future contact points as surfaces became more irregular. We quantify the inter-related effects of whisker spacing and the object's spatial frequencies, and examine the issues that arise in the presence of real-world noise, friction, and slip.

Size Constancy in Bat Biosonar? Perceptual Interaction of Object Aperture and Distance

PubMed Central

Heinrich, Melina; Wiegrebe, Lutz

2013-01-01

Perception and encoding of object size is an important feature of sensory systems. In the visual system object size is encoded by the visual angle (visual aperture) on the retina, but the aperture depends on the distance of the object. As object distance is not unambiguously encoded in the visual system, higher computational mechanisms are needed. This phenomenon is termed “size constancy”. It is assumed to reflect an automatic re-scaling of visual aperture with perceived object distance. Recently, it was found that in echolocating bats, the ‘sonar aperture’, i.e., the range of angles from which sound is reflected from an object back to the bat, is unambiguously perceived and neurally encoded. Moreover, it is well known that object distance is accurately perceived and explicitly encoded in bat sonar. Here, we addressed size constancy in bat biosonar, recruiting virtual-object techniques. Bats of the species Phyllostomus discolor learned to discriminate two simple virtual objects that only differed in sonar aperture. Upon successful discrimination, test trials were randomly interspersed using virtual objects that differed in both aperture and distance. It was tested whether the bats spontaneously assigned absolute width information to these objects by combining distance and aperture. The results showed that while the isolated perceptual cues encoding object width, aperture, and distance were all perceptually well resolved by the bats, the animals did not assign absolute width information to the test objects. This lack of sonar size constancy may result from the bats relying on different modalities to extract size information at different distances. Alternatively, it is conceivable that familiarity with a behaviorally relevant, conspicuous object is required for sonar size constancy, as it has been argued for visual size constancy. Based on the current data, it appears that size constancy is not necessarily an essential feature of sonar perception in bats. PMID:23630598

Size constancy in bat biosonar? Perceptual interaction of object aperture and distance.

PubMed

Heinrich, Melina; Wiegrebe, Lutz

2013-01-01

Perception and encoding of object size is an important feature of sensory systems. In the visual system object size is encoded by the visual angle (visual aperture) on the retina, but the aperture depends on the distance of the object. As object distance is not unambiguously encoded in the visual system, higher computational mechanisms are needed. This phenomenon is termed "size constancy". It is assumed to reflect an automatic re-scaling of visual aperture with perceived object distance. Recently, it was found that in echolocating bats, the 'sonar aperture', i.e., the range of angles from which sound is reflected from an object back to the bat, is unambiguously perceived and neurally encoded. Moreover, it is well known that object distance is accurately perceived and explicitly encoded in bat sonar. Here, we addressed size constancy in bat biosonar, recruiting virtual-object techniques. Bats of the species Phyllostomus discolor learned to discriminate two simple virtual objects that only differed in sonar aperture. Upon successful discrimination, test trials were randomly interspersed using virtual objects that differed in both aperture and distance. It was tested whether the bats spontaneously assigned absolute width information to these objects by combining distance and aperture. The results showed that while the isolated perceptual cues encoding object width, aperture, and distance were all perceptually well resolved by the bats, the animals did not assign absolute width information to the test objects. This lack of sonar size constancy may result from the bats relying on different modalities to extract size information at different distances. Alternatively, it is conceivable that familiarity with a behaviorally relevant, conspicuous object is required for sonar size constancy, as it has been argued for visual size constancy. Based on the current data, it appears that size constancy is not necessarily an essential feature of sonar perception in bats.

Optimizing the positional relationships between instruments used in laparoscopic simulation using a simple trigonometric method.

PubMed

Lorias Espinoza, Daniel; Ordorica Flores, Ricardo; Minor Martínez, Arturo; Gutiérrez Gnecchi, José Antonio

2014-06-01

Various methods for evaluating laparoscopic skill have been reported, but without detailed information on the configuration used they are difficult to reproduce. Here we present a method based on the trigonometric relationships between the instruments used in a laparoscopic training platform in order to provide a tool to aid in the reproducible assessment of surgical laparoscopic technique. The positions of the instruments were represented using triangles. Basic trigonometry was used to objectively establish the distances among the working ports RL, the placement of the optical port h', and the placement of the surgical target OT. The optimal configuration of a training platform depends on the selected working angles, the intracorporeal/extracorporeal lengths of the instrument, and the depth of the surgical target. We demonstrate that some distances, angles, and positions of the instruments are inappropriate for satisfactory laparoscopy. By applying basic trigonometric principles we can determine the ideal placement of the working ports and the optics in a simple, precise, and objective way. In addition, because the method is based on parameters known to be important in both the performance and quantitative quality of laparoscopy, the results are generalizable to different training platforms and types of laparoscopic surgery.

Time-Driven Effects on Processing Relative Clauses

ERIC Educational Resources Information Center

Schremm, Andrea; Horne, Merle; Roll, Mikael

2016-01-01

The present response time study investigated how a hypothesized time-based working memory constraint of 2-3 s affects the resolution of grammatical and semantic dependencies. Congruent and incongruent object relative (OR) and subject relative sentences were read at different presentation rates so that the distance between dependent words was…

A high spatial resolution optical pyrometer

NASA Astrophysics Data System (ADS)

Nason, D. O.; Yen, C. T.; Feigelson, R. S.; Tiller, W. A.

1990-03-01

An optical pyrometer has been developed which resolves 20 μm at a working distance of 24 in. and measures relative temperature differences of ±2 °C over the range 1000-2000 °C. The instrument is particularly suitable for measuring temperature or emissivity distributions in very small heated objects.

Associations between the Objectively Measured Office Environment and Workplace Step Count and Sitting Time: Cross-Sectional Analyses from the Active Buildings Study.

PubMed

Fisher, Abi; Ucci, Marcella; Smith, Lee; Sawyer, Alexia; Spinney, Richard; Konstantatou, Marina; Marmot, Alexi

2018-06-01

Office-based workers spend a large proportion of the day sitting and tend to have low overall activity levels. Despite some evidence that features of the external physical environment are associated with physical activity, little is known about the influence of the spatial layout of the internal environment on movement, and the majority of data use self-report. This study investigated associations between objectively-measured sitting time and activity levels and the spatial layout of office floors in a sample of UK office-based workers. Participants wore activPAL accelerometers for at least three consecutive workdays. Primary outcomes were steps and proportion of sitting time per working hour. Primary exposures were office spatial layout, which was objectively-measured by deriving key spatial variables: 'distance from each workstation to key office destinations', 'distance from participant's workstation to all other workstations', 'visibility of co-workers', and workstation 'closeness'. 131 participants from 10 organisations were included. Fifty-four per cent were female, 81% were white, and the majority had a managerial or professional role (72%) in their organisation. The average proportion of the working hour spent sitting was 0.7 (SD 0.15); participants took on average 444 (SD 210) steps per working hour. Models adjusted for confounders revealed significant negative associations between step count and distance from each workstation to all other office destinations (e.g., B = -4.66, 95% CI: -8.12, -1.12, p < 0.01) and nearest office destinations (e.g., B = -6.45, 95% CI: -11.88, -0.41, p < 0.05) and visibility of workstations when standing (B = -2.35, 95% CI: -3.53, -1.18, p < 0.001). The magnitude of these associations was small. There were no associations between spatial variables and sitting time per work hour. Contrary to our hypothesis, the further participants were from office destinations the less they walked, suggesting that changing the relative distance between workstations and other destinations on the same floor may not be the most fruitful target for promoting walking and reducing sitting in the workplace. However, reported effect sizes were very small and based on cross-sectional analyses. The approaches developed in this study could be applied to other office buildings to establish whether a specific office typology may yield more promising results.

Efficient distance calculation using the spherically-extended polytope (s-tope) model

NASA Technical Reports Server (NTRS)

Hamlin, Gregory J.; Kelley, Robert B.; Tornero, Josep

1991-01-01

An object representation scheme which allows for Euclidean distance calculation is presented. The object model extends the polytope model by representing objects as the convex hull of a finite set of spheres. An algorithm for calculating distances between objects is developed which is linear in the total number of spheres specifying the two objects.

Marked Object Recognition Multitouch Screen Printed Touchpad for Interactive Applications.

PubMed

Nunes, Jivago Serrado; Castro, Nelson; Gonçalves, Sergio; Pereira, Nélson; Correia, Vitor; Lanceros-Mendez, Senentxu

2017-12-01

The market for interactive platforms is rapidly growing, and touchscreens have been incorporated in an increasing number of devices. Thus, the area of smart objects and devices is strongly increasing by adding interactive touch and multimedia content, leading to new uses and capabilities. In this work, a flexible screen printed sensor matrix is fabricated based on silver ink in a polyethylene terephthalate (PET) substrate. Diamond shaped capacitive electrodes coupled with conventional capacitive reading electronics enables fabrication of a highly functional capacitive touchpad, and also allows for the identification of marked objects. For the latter, the capacitive signatures are identified by intersecting points and distances between them. Thus, this work demonstrates the applicability of a low cost method using royalty-free geometries and technologies for the development of flexible multitouch touchpads for the implementation of interactive and object recognition applications.

Marked Object Recognition Multitouch Screen Printed Touchpad for Interactive Applications

PubMed Central

Nunes, Jivago Serrado; Castro, Nelson; Pereira, Nélson; Correia, Vitor; Lanceros-Mendez, Senentxu

2017-01-01

The market for interactive platforms is rapidly growing, and touchscreens have been incorporated in an increasing number of devices. Thus, the area of smart objects and devices is strongly increasing by adding interactive touch and multimedia content, leading to new uses and capabilities. In this work, a flexible screen printed sensor matrix is fabricated based on silver ink in a polyethylene terephthalate (PET) substrate. Diamond shaped capacitive electrodes coupled with conventional capacitive reading electronics enables fabrication of a highly functional capacitive touchpad, and also allows for the identification of marked objects. For the latter, the capacitive signatures are identified by intersecting points and distances between them. Thus, this work demonstrates the applicability of a low cost method using royalty-free geometries and technologies for the development of flexible multitouch touchpads for the implementation of interactive and object recognition applications. PMID:29194414

Scientific rationale and strategies for a first comet mission: Report of the Comet Halley science working group

NASA Technical Reports Server (NTRS)

1977-01-01

The science objectives of a first comet mission are reviewed and related to what is known or can be expected to be learned in the near future from ground-based and near earth observations. A set of instruments and their science objectives are defined for a mission to Comet Halley during its 1985/86 apparition. The benefits from a fast flyby, a slow flyby, or a rendezvous mission and the relative impact of each on the instrument payload were assessed. The relative scientific value of encounters with the comet at distances from the sun ranging from 1 AU to 2.5 AU, including possible tradeoffs between flyby velocity and distance was considered. Pre- and post-perihelion encounters were likewise evaluated.

Peripheral Design of Progressive Addition Lenses and the Lag of Accommodation in Myopes.

PubMed

Schilling, Tim; Ohlendorf, Arne; Varnas, Saulius R; Wahl, Siegfried

2017-07-01

Insufficient accommodative response is assumed to result in myopia progression. We have investigated if the accommodative lag in myopes is different between a single vision lens (SVL) and the progressive addition lens PAL 2, clinically trialled for its ability to reduce progression of myopia, and if there exist differences in accommodative lag between PAL 2 and other PALs with the same addition power (+1.50 D). The influence of spherical SVL and four different designs of PALs that differ in the near zone width (PAL 1) or that have different signs and magnitude of horizontal gradients of mean power adjacent to their near vision zones (PAL 3 and PAL 4) on the accommodative response was investigated for different near viewing distances (40, 33, and 25 cm) in 31 subjects, aged 18 to 25 years. The SVL correction resulted in insufficient accommodative response for the near object viewing distances tested. PAL 2 did significantly reduce accommodative lag for all near object distances tested. The PAL design with a more negative horizontal mean power gradient (PAL 4) provided a lower lag of accommodation when compared with PAL 2 at the shortest object distance of 25 cm (P = 0.03) and was able to reduce the lag of accommodation to a level below the depth of focus for the higher near working distances tested. Designs of PAL with more negative horizontal mean power gradients are the most effective in lowering the lag of accommodation in myopes. This could make them good test candidates for myopia control applications.

Application of Oversampling to obtain the MTF of Digital Radiology Equipment.

NASA Astrophysics Data System (ADS)

Narváez, M.; Graffigna, J. P.; Gómez, M. E.; Romo, R.

2016-04-01

Within the objectives of theproject Medical Image Processing for QualityAssessment ofX Ray Imaging, the present research work is aimed at developinga phantomX ray image and itsassociated processing algorithms in order to evaluatethe image quality rendered by digital X ray equipment. These tools are used to measure various image parameters, among which spatial resolution shows afundamental property that can be characterized by the Modulation Transfer Function (MTF)of an imaging system [1]. After performing a thorough literature surveyon imaging quality control in digital X film in Argentine and international publications, it was decided to adopt for this work the Norm IEC 62220 1:2003 that recommends using an image edge as a testingmethod. In order to obtain the characterizing MTF, a protocol was designedfor unifying the conditions under which the images are acquired for later evaluation. The protocol implied acquiring a radiography image by means of a specific referential technique, i.e. referred either to voltage, current, time, distance focus plate (/film?) distance, or other referential parameter, and to interpret the image through a system of computed radiology or direct digital radiology. The contribution of the work stems from the fact that, even though the traditional way of evaluating an X film image quality has relied mostly on subjective methods, this work presents an objective evaluative toolfor the images obtained with a givenequipment, followed by a contrastive analysis with the renderings from other X filmimaging sets.Once the images were obtained, specific calculations were carried out. Though there exist some methods based on the subjective evaluation of the quality of image, this work offers an objective evaluation of the equipment under study. Finally, we present the results obtained on different equipment.

Novel approach for image skeleton and distance transformation parallel algorithms

NASA Astrophysics Data System (ADS)

Qing, Kent P.; Means, Robert W.

1994-05-01

Image Understanding is more important in medical imaging than ever, particularly where real-time automatic inspection, screening and classification systems are installed. Skeleton and distance transformations are among the common operations that extract useful information from binary images and aid in Image Understanding. The distance transformation describes the objects in an image by labeling every pixel in each object with the distance to its nearest boundary. The skeleton algorithm starts from the distance transformation and finds the set of pixels that have a locally maximum label. The distance algorithm has to scan the entire image several times depending on the object width. For each pixel, the algorithm must access the neighboring pixels and find the maximum distance from the nearest boundary. It is a computational and memory access intensive procedure. In this paper, we propose a novel parallel approach to the distance transform and skeleton algorithms using the latest VLSI high- speed convolutional chips such as HNC's ViP. The algorithm speed is dependent on the object's width and takes (k + [(k-1)/3]) * 7 milliseconds for a 512 X 512 image with k being the maximum distance of the largest object. All objects in the image will be skeletonized at the same time in parallel.

Virtual-reality techniques resolve the visual cues used by fruit flies to evaluate object distances.

PubMed

Schuster, Stefan; Strauss, Roland; Götz, Karl G

2002-09-17

Insects can estimate distance or time-to-contact of surrounding objects from locomotion-induced changes in their retinal position and/or size. Freely walking fruit flies (Drosophila melanogaster) use the received mixture of different distance cues to select the nearest objects for subsequent visits. Conventional methods of behavioral analysis fail to elucidate the underlying data extraction. Here we demonstrate first comprehensive solutions of this problem by substituting virtual for real objects; a tracker-controlled 360 degrees panorama converts a fruit fly's changing coordinates into object illusions that require the perception of specific cues to appear at preselected distances up to infinity. An application reveals the following: (1) en-route sampling of retinal-image changes accounts for distance discrimination within a surprising range of at least 8-80 body lengths (20-200 mm). Stereopsis and peering are not involved. (2) Distance from image translation in the expected direction (motion parallax) outweighs distance from image expansion, which accounts for impact-avoiding flight reactions to looming objects. (3) The ability to discriminate distances is robust to artificially delayed updating of image translation. Fruit flies appear to interrelate self-motion and its visual feedback within a surprisingly long time window of about 2 s. The comparative distance inspection practiced in the small fruit fly deserves utilization in self-moving robots.

Randomized Approaches for Nearest Neighbor Search in Metric Space When Computing the Pairwise Distance Is Extremely Expensive

NASA Astrophysics Data System (ADS)

Wang, Lusheng; Yang, Yong; Lin, Guohui

Finding the closest object for a query in a database is a classical problem in computer science. For some modern biological applications, computing the similarity between two objects might be very time consuming. For example, it takes a long time to compute the edit distance between two whole chromosomes and the alignment cost of two 3D protein structures. In this paper, we study the nearest neighbor search problem in metric space, where the pair-wise distance between two objects in the database is known and we want to minimize the number of distances computed on-line between the query and objects in the database in order to find the closest object. We have designed two randomized approaches for indexing metric space databases, where objects are purely described by their distances with each other. Analysis and experiments show that our approaches only need to compute O(logn) objects in order to find the closest object, where n is the total number of objects in the database.

Problems in depth perception : perceived size and distance of familiar objects.

DOT National Transportation Integrated Search

1966-06-01

Judgments of the distance of familiar objects, especially other aircraft, are critical aspects of flight safety. In this study, the perception of distance as a function of the retinal size of a familiar object was investigated by simulating a station...

Method and System for Determining Relative Displacement and Heading for Navigation

NASA Technical Reports Server (NTRS)

Sheikh, Suneel Ismail (Inventor); Pines, Darryll J. (Inventor); Conroy, Joseph Kim (Inventor); Spiridonov, Timofey N. (Inventor)

2015-01-01

A system and method for determining a location of a mobile object is provided. The system determines the location of the mobile object by determining distances between a plurality of sensors provided on a first and second movable parts of the mobile object. A stride length, heading, and separation distance between the first and second movable parts are computed based on the determined distances and the location of the mobile object is determined based on the computed stride length, heading, and separation distance.

Optimizing the depth of field for short object distance of capsule endoscope

NASA Astrophysics Data System (ADS)

Ou-Yang, Mang; Huang, Shih-Wei; Su, Wei-Kai; Feng, Han-Ming; Chen, Zhao-Yu; Wu, Hsien-Ming; Kuo, Yi-Ting

2008-02-01

Research of depth of field (DOF) for capsule endoscope is important for the reason that the shapes of the object plane of the intestine or the stomach are curve surfaces of "<" shape or "c" shape. The depth of field is dependent on following factors: focal length, circle of confusion, aperture, and subject distance. The first three factors are improved for wide view angle in prior paper and determined by the chosen sensor, and it is not going against depth of field. Last factor, subject distance, is the more freedom to enlarge the depth of field. However, depth of field is the range between near depth of field limit and far depth of field limit that are acceptably sharp. The fraction of the depth of field behind the focus is always large then the one in front of the focus distance. The depth of field does change with object distance, and it is increasing as object distance is increasing. But the object distance of the design for capsule endoscope is short. The object distance setting in front of the dorm is more efficient to use the depth of field than the one setting at the dome top. Therefore there is an appropriate design of object distance to make depth of field be used efficiently to inspect curve surface of intestine and stomach. The more vision information of inspect digestive system is get and is compared easily to diagnose patients' condition under wide and efficient range of depth of field.

High spatial resolution detection of low-energy electrons using an event-counting method, application to point projection microscopy

NASA Astrophysics Data System (ADS)

Salançon, Evelyne; Degiovanni, Alain; Lapena, Laurent; Morin, Roger

2018-04-01

An event-counting method using a two-microchannel plate stack in a low-energy electron point projection microscope is implemented. 15 μm detector spatial resolution, i.e., the distance between first-neighbor microchannels, is demonstrated. This leads to a 7 times better microscope resolution. Compared to previous work with neutrons [Tremsin et al., Nucl. Instrum. Methods Phys. Res., Sect. A 592, 374 (2008)], the large number of detection events achieved with electrons shows that the local response of the detector is mainly governed by the angle between the hexagonal structures of the two microchannel plates. Using this method in point projection microscopy offers the prospect of working with a greater source-object distance (350 nm instead of 50 nm), advancing toward atomic resolution.

Neighborhood educational disparities in active commuting among women: the effect of distance between the place of residence and the place of work/study (an ACTI-Cités study).

PubMed

Perchoux, Camille; Nazare, Julie-Anne; Benmarhnia, Tarik; Salze, Paul; Feuillet, Thierry; Hercberg, Serge; Hess, Franck; Menai, Mehdi; Weber, Christiane; Charreire, Hélène; Enaux, Christophe; Oppert, Jean-Michel; Simon, Chantal

2017-06-12

Active transportation has been associated with favorable health outcomes. Previous research highlighted the influence of neighborhood educational level on active transportation. However, little is known regarding the effect of commuting distance on social disparities in active commuting. In this regard, women have been poorly studied. The objective of this paper was to evaluate the relationship between neighborhood educational level and active commuting, and to assess whether the commuting distance modifies this relationship in adult women. This cross-sectional study is based on a subsample of women from the Nutrinet-Santé web-cohort (N = 1169). Binomial, log-binomial and negative binomial regressions were used to assess the associations between neighborhood education level and (i) the likelihood of reporting any active commuting time, and (ii) the share of commuting time made by active transportation modes. Potential effect measure modification of distance to work on the previous associations was assessed both on the additive and the multiplicative scales. Neighborhood education level was positively associated with the probability of reporting any active commuting time (relative risk = 1.774; p < 0.05) and the share of commuting time spent active (relative risk = 1.423; p < 0.05). The impact of neighborhood education was greater at long distances to work for both outcomes. Our results suggest that neighborhood educational disparities in active commuting tend to increase with commuting distance among women. Further research is needed to provide geographically driven guidance for health promotion intervention aiming at reducing disparities in active transportation among socioeconomic groups.

[Pitfalls in the prescription of reading glasses].

PubMed

Krause, H-K

2011-04-01

People in the second half of their lives often require reading glasses. A basic requirement for determining suitable reading glasses is measurement of the patient's accommodation, which describes the change in the eye's optical power caused by the attempt to clearly focus on an object at a certain distance. The maximum accommodation performance of a person already begins to decline from the age of 40 onwards. When it becomes increasingly difficult to adjust to the typical reading distance of 40 cm, one speaks of presbyopia: age-related farsightedness. This contribution describes two appropriate methods for determining the strength of reading glasses: determination of the maximum accommodation performance by measuring the near point distance and determination of the maximum accommodation effort by measuring the relative positive and negative accommodation. Optimal reading glasses enable the patient to focus sharply on something from the working distance that is closer but also on something that is further away.

Quantitative endoscopy: initial accuracy measurements.

PubMed

Truitt, T O; Adelman, R A; Kelly, D H; Willging, J P

2000-02-01

The geometric optics of an endoscope can be used to determine the absolute size of an object in an endoscopic field without knowing the actual distance from the object. This study explores the accuracy of a technique that estimates absolute object size from endoscopic images. Quantitative endoscopy involves calibrating a rigid endoscope to produce size estimates from 2 images taken with a known traveled distance between the images. The heights of 12 samples, ranging in size from 0.78 to 11.80 mm, were estimated with this calibrated endoscope. Backup distances of 5 mm and 10 mm were used for comparison. The mean percent error for all estimated measurements when compared with the actual object sizes was 1.12%. The mean errors for 5-mm and 10-mm backup distances were 0.76% and 1.65%, respectively. The mean errors for objects <2 mm and > or =2 mm were 0.94% and 1.18%, respectively. Quantitative endoscopy estimates endoscopic image size to within 5% of the actual object size. This method remains promising for quantitatively evaluating object size from endoscopic images. It does not require knowledge of the absolute distance of the endoscope from the object, rather, only the distance traveled by the endoscope between images.

Using guided inquiry to teach academic language

NASA Astrophysics Data System (ADS)

Parent, Kelley

2017-12-01

Introducing new physics phenomena through inquiry labs has been a staple of the successful physics teacher for years. Introducing new vocabulary through lab work, however, is less common. This paper offers an example of a simple and short lab that does just that, and one that I have found to be quite useful in my college prep physics courses to help students construct (and retain) functional definitions of the oft-transposed terms distance and displacement. A standard definition for displacement is a change in an object's position, while distance would be the entire path traveled by the object, yet my students were using the two terms interchangeably, often saying distance when they really should have referred to displacement. I wanted them to be able to clearly distinguish between the two terms, so I designed a brief experiment that allows students the chance to engage with the concept. My colleagues and I have found that putting the students in charge of their learning with this simple activity helps the students better understand the difference between these two terms.

Integrated Force and Distance Sensing using Elastomer-Embedded Commodity Proximity Sensors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Radhen; Cox, Rebecca E.; Correll, Nikolaus

We describe a combined proximity, contact and force (PCF) sensor based on a commodity infrared distance sensor embedded in a transparent elastomer with applications in robotic manipulation. Prior to contact, the sensor works as a distance sensor (0{6 cm), whereas after contact the material doubles as a spring, with force proportional to the compression of the elastomer (0{5 N). We describe its principle of operation and design parameters, including polymer thickness, mixing ratio, and emitter current, and show that the sensor response has an in ection point at contact that is independent of an object's surface properties, making it amore » robust detector for contact events. We then demonstrate how arrays of sensors, custom made for a standard Baxter gripper as well as embedded in the nger of the Kinova hand, can be used to (1) improve gripper alignment during grasping, (2) determine contact points with objects, (3) obtain simple 3D models using both proximity and touch, and (4) register point clouds from touch and RGB-D data.« less

The fundamentals of average local variance--Part I: Detecting regular patterns.

PubMed

Bøcher, Peder Klith; McCloy, Keith R

2006-02-01

The method of average local variance (ALV) computes the mean of the standard deviation values derived for a 3 x 3 moving window on a successively coarsened image to produce a function of ALV versus spatial resolution. In developing ALV, the authors used approximately a doubling of the pixel size at each coarsening of the image. They hypothesized that ALV is low when the pixel size is smaller than the size of scene objects because the pixels on the object will have similar response values. When the pixel and objects are of similar size, they will tend to vary in response and the ALV values will increase. As the size of pixels increase further, more objects will be contained in a single pixel and ALV will decrease. The authors showed that various cover types produced single peak ALV functions that inexplicitly peaked when the pixel size was 1/2 to 3/4 of the object size. This paper reports on work done to explore the characteristics of the various forms of the ALV function and to understand the location of the peaks that occur in this function. The work was conducted using synthetically generated image data. The investigation showed that the hypothesis originally proposed in is not adequate. A new hypothesis is proposed that the ALV function has peak locations that are related to the geometric size of pattern structures in the scene. These structures are not always the same as scene objects. Only in cases where the size of and separation between scene objects are equal does the ALV function detect the size of the objects. In situations where the distance between scene objects are larger than their size, the ALV function has a peak at the object separation, not at the object size. This work has also shown that multiple object structures of different sizes and distances in the image provide multiple peaks in the ALV function and that some of these structures are not implicitly recognized as such from our perspective. However, the magnitude of these peaks depends on the response mix in the structures, complicating their interpretation and analysis. The analysis of the ALV Function is, thus, more complex than that generally reported in the literature.

Measuring distance “as the horse runs”: Cross-scale comparison of terrain-based metrics

USGS Publications Warehouse

Buttenfield, Barbara P.; Ghandehari, M; Leyk, S; Stanislawski, Larry V.; Brantley, M E; Qiang, Yi

2016-01-01

Distance metrics play significant roles in spatial modeling tasks, such as flood inundation (Tucker and Hancock 2010), stream extraction (Stanislawski et al. 2015), power line routing (Kiessling et al. 2003) and analysis of surface pollutants such as nitrogen (Harms et al. 2009). Avalanche risk is based on slope, aspect, and curvature, all directly computed from distance metrics (Gutiérrez 2012). Distance metrics anchor variogram analysis, kernel estimation, and spatial interpolation (Cressie 1993). Several approaches are employed to measure distance. Planar metrics measure straight line distance between two points (“as the crow flies”) and are simple and intuitive, but suffer from uncertainties. Planar metrics assume that Digital Elevation Model (DEM) pixels are rigid and flat, as tiny facets of ceramic tile approximating a continuous terrain surface. In truth, terrain can bend, twist and undulate within each pixel.Work with Light Detection and Ranging (lidar) data or High Resolution Topography to achieve precise measurements present challenges, as filtering can eliminate or distort significant features (Passalacqua et al. 2015). The current availability of lidar data is far from comprehensive in developed nations, and non-existent in many rural and undeveloped regions. Notwithstanding computational advances, distance estimation on DEMs has never been systematically assessed, due to assumptions that improvements are so small that surface adjustment is unwarranted. For individual pixels inaccuracies may be small, but additive effects can propagate dramatically, especially in regional models (e.g., disaster evacuation) or global models (e.g., sea level rise) where pixels span dozens to hundreds of kilometers (Usery et al 2003). Such models are increasingly common, lending compelling reasons to understand shortcomings in the use of planar distance metrics. Researchers have studied curvature-based terrain modeling. Jenny et al. (2011) use curvature to generate hierarchical terrain models. Schneider (2001) creates a ‘plausibility’ metric for DEM-extracted structure lines. d’Oleire- Oltmanns et al. (2014) adopt object-based image processing as an alternative to working with DEMs; acknowledging the pre-processing involved in converting terrain into an object model is computationally intensive, and likely infeasible for some applications.This paper compares planar distance with surface adjusted distance, evolving from distance “as the crow flies” to distance “as the horse runs”. Several methods are compared for DEMs spanning a range of resolutions for the study area and validated against a 3 meter (m) lidar data benchmark. Error magnitudes vary with pixel size and with the method of surface adjustment. The rate of error increase may also vary with landscape type (terrain roughness, precipitation regimes and land settlement patterns). Cross-scale analysis for a single study area is reported here. Additional areas will be presented at the conference.

Cool Flame Quenching

NASA Technical Reports Server (NTRS)

Pearlman, Howard; Chapek, Richard

2001-01-01

Cool flame quenching distances are generally presumed to be larger than those associated with hot flames, because the quenching distance scales with the inverse of the flame propagation speed, and cool flame propagation speeds are often times slower than those associated with hot flames. To date, this presumption has never been put to a rigorous test, because unstirred, non-isothermal cool flame studies on Earth are complicated by natural convection. Moreover, the critical Peclet number (Pe) for quenching of cool flames has never been established and may not be the same as that associated with wall quenching due to conduction heat loss in hot flames, Pe approx. = 40-60. The objectives of this ground-based study are to: (1) better understand the role of conduction heat loss and species diffusion on cool flame quenching (i.e., Lewis number effects), (2) determine cool flame quenching distances (i.e, critical Peclet number, Pe) for different experimental parameters and vessel surface pretreatments, and (3) understand the mechanisms that govern the quenching distances in premixtures that support cool flames as well as hot flames induced by spark-ignition. Objective (3) poses a unique fire safety hazard if conditions exist where cool flame quenching distances are smaller than those associated with hot flames. For example, a significant, yet unexplored risk, can occur if a multi-stage ignition (a cool flame that transitions to a hot flame) occurs in a vessel size that is smaller than that associated with the hot quenching distance. To accomplish the above objectives, a variety of hydrocarbon-air mixtures will be tested in a static reactor at elevated temperature in the laboratory (1g). In addition, reactions with chemical induction times that are sufficiently short will be tested aboard NASA's KC-135 microgravity (mu-g) aircraft. The mu-g results will be compared to a numerical model that includes species diffusion, heat conduction, and a skeletal kinetic mechanism, following the work on diffusion-controlled cool flames by Fairlie et,al., 2000.

Construction and validation of a distance learning module on premedication antisepsis for nursing professionals.

PubMed

Pereira, Barbara Juliana da Costa; Mendes, Isabel Amélia Costa; Beatriz Maria, Jorge; Mazzo, Alessandra

2013-11-01

The aim of this descriptive study, carried out at a public university, was to design, develop, and validate a distance learning module on intramuscular premedication antisepsis. The content was introduced in the Modular Object-Oriented Dynamic Learning Environment, based on the Systematic Model for Web-Based Training projects. Ten nurses and information technologists at work consented to participate, in compliance with ethical guidelines, and answered a questionnaire to validate the Virtual Learning Environment. The educational aspects of the environment interface were mostly evaluated as "excellent," whereas the assessment of didactic resources indicated interactivity difficulties. It is concluded that distance learning is an important tool for the teaching of premedication antisepsis. To ensure its effectiveness, appropriate methods and interactive devices must be used.

Model-Based Least Squares Reconstruction of Coded Source Neutron Radiographs: Integrating the ORNL HFIR CG1D Source Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santos-Villalobos, Hector J; Gregor, Jens; Bingham, Philip R

2014-01-01

At the present, neutron sources cannot be fabricated small and powerful enough in order to achieve high resolution radiography while maintaining an adequate flux. One solution is to employ computational imaging techniques such as a Magnified Coded Source Imaging (CSI) system. A coded-mask is placed between the neutron source and the object. The system resolution is increased by reducing the size of the mask holes and the flux is increased by increasing the size of the coded-mask and/or the number of holes. One limitation of such system is that the resolution of current state-of-the-art scintillator-based detectors caps around 50um. Tomore » overcome this challenge, the coded-mask and object are magnified by making the distance from the coded-mask to the object much smaller than the distance from object to detector. In previous work, we have shown via synthetic experiments that our least squares method outperforms other methods in image quality and reconstruction precision because of the modeling of the CSI system components. However, the validation experiments were limited to simplistic neutron sources. In this work, we aim to model the flux distribution of a real neutron source and incorporate such a model in our least squares computational system. We provide a full description of the methodology used to characterize the neutron source and validate the method with synthetic experiments.« less

The Application of Werner and Kaplan's Concept of "Distancing" to Children Who Are Deaf-Blind

ERIC Educational Resources Information Center

Bruce, Susan M.

2005-01-01

Through the process of distancing, children develop an understanding of the differences between themselves and others, themselves and objects, and objects and representations. Adults can support progressive distancing in children who are congenitally deaf-blind by applying strategies, such as the hand-under-hand exploration of objects, the…

Simulations of Liners and Test Objects for a New Atlas Advanced Radiography Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

D. V. Morgan; S. Iversen; R. A. Hilko

2002-06-01

The Advanced Radiographic Source (ARS) will improve the data significantly due to its smaller source width. Because of the enhanced ARS output, larger source-to-object distances are a reality. The harder ARS source will allow radiography of thick high-Z targets. The five different spectral simulations resulted in similar imaging detector weighted transmission. This work used a limited set of test objects and imaging detectors. Other test objects and imaging detectors could possibly change the MVp-sensitivity result. The effect of material motion blur must be considered for the ARS due to the expected smaller X-ray source size. This study supports the originalmore » 1.5-MVp value.« less

Investigation of sparsity metrics for autofocusing in digital holographic microscopy

NASA Astrophysics Data System (ADS)

Fan, Xin; Healy, John J.; Hennelly, Bryan M.

2017-05-01

Digital holographic microscopy (DHM) is an optoelectronic technique that is made up of two parts: (i) the recording of the interference pattern of the diffraction pattern of an object and a known reference wavefield using a digital camera and (ii) the numerical reconstruction of the complex object wavefield using the recorded interferogram and a distance parameter as input. The latter is based on the simulation of optical propagation from the camera plane to a plane at any arbitrary distance from the camera. A key advantage of DHM over conventional microscopy is that both the phase and intensity information of the object can be recovered at any distance, using only one capture, and this facilitates the recording of scenes that may change dynamically and that may otherwise go in and out of focus. Autofocusing using traditional microscopy requires mechanical movement of the translation stage or the microscope objective, and multiple image captures that are then compared using some metric. Autofocusing in DHM is similar, except that the sequence of intensity images, to which the metric is applied, is generated numerically from a single capture. We recently investigated the application of a number of sparsity metrics for DHM autofocusing and in this paper we extend this work to include more such metrics, and apply them over a greater range of biological diatom cells and magnification/numerical apertures. We demonstrate for the first time that these metrics may be grouped together according to matching behavior following high pass filtering.

Distance Measurements In X-Ray Pictures

NASA Astrophysics Data System (ADS)

Forsgren, Per-Ola

1987-10-01

In this paper, a measurement method for the distance between binary objects will be presented. It has been developed for a specific purpose, the evaluation of rheumatic disease, but should be useful also in other applications. It is based on a distance map in the area between binary objects. A skeleton is extracted from the distance map by searching for local maxima. The distance measure is based on the average of skelton points in a defined measurement area. An objective criterion for selection of measurement points on the skeleton is proposed. Preliminary results indicate that good repeatability is attained.

Object locating system

DOEpatents

Novak, J.L.; Petterson, B.

1998-06-09

A sensing system locates an object by sensing the object`s effect on electric fields. The object`s effect on the mutual capacitance of electrode pairs varies according to the distance between the object and the electrodes. A single electrode pair can sense the distance from the object to the electrodes. Multiple electrode pairs can more precisely locate the object in one or more dimensions. 12 figs.

Depletion forces on circular and elliptical obstacles induced by active matter

NASA Astrophysics Data System (ADS)

Leite, L. R.; Lucena, D.; Potiguar, F. Q.; Ferreira, W. P.

2016-12-01

Depletion forces exerted by self-propelled particles on circular and elliptical passive objects are studied using numerical simulations. We show that a bath of active particles can induce repulsive and attractive forces which are sensitive to the shape and orientation of the passive objects (either horizontal or vertical ellipses). The resultant force on the passive objects due to the active particles is studied as a function of the shape and orientation of the passive objects, magnitude of the angular noise, and distance between the passive objects. By increasing the distance between obstacles the magnitude of the repulsive depletion force increases, as long as such a distance is less than one active particle diameter. For longer distances, the magnitude of the force always decreases with increasing distance. We also found that attractive forces may arise for vertical ellipses at high enough area fraction.

Depletion forces on circular and elliptical obstacles induced by active matter.

PubMed

Leite, L R; Lucena, D; Potiguar, F Q; Ferreira, W P

2016-12-01

Depletion forces exerted by self-propelled particles on circular and elliptical passive objects are studied using numerical simulations. We show that a bath of active particles can induce repulsive and attractive forces which are sensitive to the shape and orientation of the passive objects (either horizontal or vertical ellipses). The resultant force on the passive objects due to the active particles is studied as a function of the shape and orientation of the passive objects, magnitude of the angular noise, and distance between the passive objects. By increasing the distance between obstacles the magnitude of the repulsive depletion force increases, as long as such a distance is less than one active particle diameter. For longer distances, the magnitude of the force always decreases with increasing distance. We also found that attractive forces may arise for vertical ellipses at high enough area fraction.

Object locating system

DOEpatents

Novak, James L.; Petterson, Ben

1998-06-09

A sensing system locates an object by sensing the object's effect on electric fields. The object's effect on the mutual capacitance of electrode pairs varies according to the distance between the object and the electrodes. A single electrode pair can sense the distance from the object to the electrodes. Multiple electrode pairs can more precisely locate the object in one or more dimensions.

Enhanced Graphics for Extended Scale Range

NASA Technical Reports Server (NTRS)

Hanson, Andrew J.; Chi-Wing Fu, Philip

2012-01-01

Enhanced Graphics for Extended Scale Range is a computer program for rendering fly-through views of scene models that include visible objects differing in size by large orders of magnitude. An example would be a scene showing a person in a park at night with the moon, stars, and galaxies in the background sky. Prior graphical computer programs exhibit arithmetic and other anomalies when rendering scenes containing objects that differ enormously in scale and distance from the viewer. The present program dynamically repartitions distance scales of objects in a scene during rendering to eliminate almost all such anomalies in a way compatible with implementation in other software and in hardware accelerators. By assigning depth ranges correspond ing to rendering precision requirements, either automatically or under program control, this program spaces out object scales to match the precision requirements of the rendering arithmetic. This action includes an intelligent partition of the depth buffer ranges to avoid known anomalies from this source. The program is written in C++, using OpenGL, GLUT, and GLUI standard libraries, and nVidia GEForce Vertex Shader extensions. The program has been shown to work on several computers running UNIX and Windows operating systems.

Long-working-distance fluorescence microscope with high-numerical-aperture objectives for variable-magnification imaging in live mice from macro- to subcellular

NASA Astrophysics Data System (ADS)

Kimura, Hiroaki; Momiyama, Masashi; Tomita, Katsuro; Tsuchiya, Hiroyuki; Hoffman, Robert M.

2010-11-01

We demonstrate the development of a long-working-distance fluorescence microscope with high-numerical-aperture objectives for variable-magnification imaging in live mice from macro- to subcellular. To observe cytoplasmic and nuclear dynamics of cancer cells in the living mouse, 143B human osteosarcoma cells are labeled with green fluorescent protein in the nucleus and red fluorescent protein in the cytoplasm. These dual-color cells are injected by a vascular route in an abdominal skin flap in nude mice. The mice are then imaged with the Olympus MVX10 macroview fluorescence microscope. With the MVX10, the nuclear and cytoplasmic behavior of cancer cells trafficking in blood vessels of live mice is observed. We also image lung metastases in live mice from the macro- to the subcellular level by opening the chest wall and imaging the exposed lung in live mice. Injected splenocytes, expressing cyan fluorescent protein, could also be imaged on the lung of live mice. We demonstrate that the MVX10 microscope offers the possibility of full-range in vivo fluorescence imaging from macro- to subcellular and should enable widespread use of powerful imaging technologies enabled by genetic reporters and other fluorophores.

New Mysteries at Chiron

NASA Technical Reports Server (NTRS)

Elliot, James L.

1998-01-01

Considered as a comet, Chiron is unusual in two respects: (1) it exhibits outbursts at great distances from the sun (nearly up to its aphelion distance of 18.9 AU), and (2) its nucleus is much larger than any other known comet. It is similar in size, however, to the recently discovered Kuiper belt objects, leading to the conjecture that Chiron is closely related to these objects, but its chaotic orbit has brought it much closer to the sun. Our work with the Kuiper Airborne Observatory resulted in the first stellar occultation by Chiron observed simultaneously at visible and infrared wavelengths. We detected four features in the coma, with different degrees of certainty. Our conclusions about Chiron from this work and a previous stellar occultation are: (1) the jet-like features observed provide evidence that the coma material originates from just a few, small active areas, rather than uniform sublimation; (2) a bound coma has possibly been detected; (3) the particle radii in at least one of the jet-like features are larger than 0.25 gm; (4) material in Chiron's orbit plane has likely been detected; and (5) the radius of Chiron's nucleus lies between 83 and 156 km.

Depth Perception in Space (Artist's Concept)

NASA Technical Reports Server (NTRS)

2007-01-01

This artist's concept shows how astronomers use the unique orbit of NASA's Spitzer Space Telescope and a depth-perceiving trick called parallax to determine the distance of dark planets, black holes and failed stars that lurk invisibly among us. These objects do not produce light, and are too faint to detect from Earth. However, astronomers can deduce their presence from the way they affect the light from background objects. When such a dark body passes in front of a bright star, its gravity warps the path of the star's light and causes it to brighten -- this process is called gravitational microlensing.

By comparing the 'peak brightness' of the microlensing event from two perspectives -- Earth and Spitzer -- scientists can determine how far away the dark object is. Peak brightness is the moment when the observer, the dark object and background star are most closely aligned.

Humans naturally use parallax to determine distance -- this is commonly referred to as depth perception. In the case of humans, each eye sees the position of an object differently. The brain takes each eye's perspective, and instantaneously calculates how far away the object is. In space, astronomers can use the same trick to determine the distance of an invisible dark object.

In this illustration, the dark object is the moving black ball between Earth, Spitzer and our neighboring galaxy the Small Magellanic Cloud (SMC; bottom right).

To determine the object's distance, astronomers observe the microlensing event at its 'peak brightness' from Earth when the dark object crosses our line-of-sight (dashed line) to a given star in the SMC. This represents one perspective, like looking at an object with only your left eye.

To get the other 'right eye' perspective, astronomers also observe the peak brightness with Spitzer when the object later moves through its line-of-sight. Because astronomers know the exact distance between Earth and Spitzer, they can determine the dark body's speed by timing how long it took for Spitzer to see peak brightness after astronomers observed the event on Earth. Using trigonometric equations and graphs to do the 'brain's' job, scientists can infer the dark body's distance.

The scales in this diagram are greatly exaggerated for clarity. The distance between Spitzer and the Earth is miniscule in comparison to the distance to the dark object and SMC. Since microlensing events require extremely precise alignments, even such a tiny separation is enough to measure these objects out to tremendous distances.

An Aggregated Method for Determining Railway Defects and Obstacle Parameters

NASA Astrophysics Data System (ADS)

Loktev, Daniil; Loktev, Alexey; Stepanov, Roman; Pevzner, Viktor; Alenov, Kanat

2018-03-01

The method of combining algorithms of image blur analysis and stereo vision to determine the distance to objects (including external defects of railway tracks) and the speed of moving objects-obstacles is proposed. To estimate the deviation of the distance depending on the blur a statistical approach, logarithmic, exponential and linear standard functions are used. The statistical approach includes a method of estimating least squares and the method of least modules. The accuracy of determining the distance to the object, its speed and direction of movement is obtained. The paper develops a method of determining distances to objects by analyzing a series of images and assessment of depth using defocusing using its aggregation with stereoscopic vision. This method is based on a physical effect of dependence on the determined distance to the object on the obtained image from the focal length or aperture of the lens. In the calculation of the blur spot diameter it is assumed that blur occurs at the point equally in all directions. According to the proposed approach, it is possible to determine the distance to the studied object and its blur by analyzing a series of images obtained using the video detector with different settings. The article proposes and scientifically substantiates new and improved existing methods for detecting the parameters of static and moving objects of control, and also compares the results of the use of various methods and the results of experiments. It is shown that the aggregate method gives the best approximation to the real distances.

Clustering analysis of line indices for LAMOST spectra with AstroStat

NASA Astrophysics Data System (ADS)

Chen, Shu-Xin; Sun, Wei-Min; Yan, Qi

2018-06-01

The application of data mining in astronomical surveys, such as the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, provides an effective approach to automatically analyze a large amount of complex survey data. Unsupervised clustering could help astronomers find the associations and outliers in a big data set. In this paper, we employ the k-means method to perform clustering for the line index of LAMOST spectra with the powerful software AstroStat. Implementing the line index approach for analyzing astronomical spectra is an effective way to extract spectral features for low resolution spectra, which can represent the main spectral characteristics of stars. A total of 144 340 line indices for A type stars is analyzed through calculating their intra and inter distances between pairs of stars. For intra distance, we use the definition of Mahalanobis distance to explore the degree of clustering for each class, while for outlier detection, we define a local outlier factor for each spectrum. AstroStat furnishes a set of visualization tools for illustrating the analysis results. Checking the spectra detected as outliers, we find that most of them are problematic data and only a few correspond to rare astronomical objects. We show two examples of these outliers, a spectrum with abnormal continuumand a spectrum with emission lines. Our work demonstrates that line index clustering is a good method for examining data quality and identifying rare objects.

The Moon Illusion, II: The moon's apparent size is a function of the presence or absence of terrain.

PubMed

Rock, I; Kaufman, L

1962-06-22

We have examined the two types of explanations of the moon illusion-the egocentric, in which the differences in direction of the horizon and the zenith moons are thought of in relation to different angles of regard of the observer, and the objective, in which the presence or absence of the terrain is considered crucial. The former type is exemplified chiefly by the eye-elevation hypothesis in the work of Boring and his colleagues; the latter, by the apparent-distance hypothesis based on the superior cues to distance provided by the terrain. Boring had rejected the apparent-distance hypothesis on the grounds that the horizon moon is reported as nearer, not farther away, by most observers. He then performed experiments which supported the eye-elevation hypothesis.

Spatial and kinematic structure of Monoceros star-forming region

NASA Astrophysics Data System (ADS)

Costado, M. T.; Alfaro, E. J.

2018-05-01

The principal aim of this work is to study the velocity field in the Monoceros star-forming region using the radial velocity data available in the literature, as well as astrometric data from the Gaia first release. This region is a large star-forming complex formed by two associations named Monoceros OB1 and OB2. We have collected radial velocity data for more than 400 stars in the area of 8 × 12 deg2 and distance for more than 200 objects. We apply a clustering analysis in the subspace of the phase space formed by angular coordinates and radial velocity or distance data using the Spectrum of Kinematic Grouping methodology. We found four and three spatial groupings in radial velocity and distance variables, respectively, corresponding to the Local arm, the central clusters forming the associations and the Perseus arm, respectively.

Anterior ankle arthroscopy, distraction or dorsiflexion?

PubMed

de Leeuw, Peter A J; Golanó, Pau; Clavero, Joan A; van Dijk, C Niek

2010-05-01

Anterior ankle arthroscopy can basically be performed by two different methods; the dorsiflexion- or distraction method. The objective of this study was to determine the size of the anterior working area for both the dorsiflexion and distraction method. The anterior working area is anteriorly limited by the overlying anatomy which includes the neurovascular bundle. We hypothesize that in ankle dorsiflexion the anterior neurovascular bundle will move away anteriorly from the ankle joint, whereas in ankle distraction the anterior neurovascular bundle is pulled tight towards the joint, thereby decreasing the safe anterior working area. Six fresh frozen ankle specimens, amputated above the knee, were scanned with computed tomography. Prior to scanning the anterior tibial artery was injected with contrast fluid and subsequently each ankle was scanned both in ankle dorsiflexion and in distraction. A special device was developed to reproducibly obtain ankle dorsiflexion and distraction in the computed tomography scanner. The distance between the anterior border of the inferior tibial articular facet and the posterior border of the anterior tibial artery was measured. The median distance from the anterior border of the inferior tibial articular facet to the posterior border of the anterior tibial artery in ankle dorsiflexion and distraction was 0.9 cm (range 0.7-1.5) and 0.7 cm (range 0.5-0.8), respectively. The distance in ankle dorsiflexion significantly exceeded the distance in ankle distraction (P = 0.03). The current study shows a significantly increased distance between the anterior distal tibia and the overlying anterior neurovascular bundle with the ankle in a slightly dorsiflexed position as compared to the distracted ankle position. We thereby conclude that the distracted ankle position puts the neurovascular structures more at risk for iatrogenic damage when performing anterior ankle arthroscopy.

Anterior ankle arthroscopy, distraction or dorsiflexion?

PubMed Central

Golanó, Pau; Clavero, Joan A.; van Dijk, C. Niek

2010-01-01

Anterior ankle arthroscopy can basically be performed by two different methods; the dorsiflexion- or distraction method. The objective of this study was to determine the size of the anterior working area for both the dorsiflexion and distraction method. The anterior working area is anteriorly limited by the overlying anatomy which includes the neurovascular bundle. We hypothesize that in ankle dorsiflexion the anterior neurovascular bundle will move away anteriorly from the ankle joint, whereas in ankle distraction the anterior neurovascular bundle is pulled tight towards the joint, thereby decreasing the safe anterior working area. Six fresh frozen ankle specimens, amputated above the knee, were scanned with computed tomography. Prior to scanning the anterior tibial artery was injected with contrast fluid and subsequently each ankle was scanned both in ankle dorsiflexion and in distraction. A special device was developed to reproducibly obtain ankle dorsiflexion and distraction in the computed tomography scanner. The distance between the anterior border of the inferior tibial articular facet and the posterior border of the anterior tibial artery was measured. The median distance from the anterior border of the inferior tibial articular facet to the posterior border of the anterior tibial artery in ankle dorsiflexion and distraction was 0.9 cm (range 0.7–1.5) and 0.7 cm (range 0.5–0.8), respectively. The distance in ankle dorsiflexion significantly exceeded the distance in ankle distraction (P = 0.03). The current study shows a significantly increased distance between the anterior distal tibia and the overlying anterior neurovascular bundle with the ankle in a slightly dorsiflexed position as compared to the distracted ankle position. We thereby conclude that the distracted ankle position puts the neurovascular structures more at risk for iatrogenic damage when performing anterior ankle arthroscopy. PMID:20217392

Distance comparisons in virtual reality: effects of path, context, and age

PubMed Central

van der Ham, Ineke J. M.; Baalbergen, Heleen; van der Heijden, Peter G. M.; Postma, Albert; Braspenning, Merel; van der Kuil, Milan N. A.

2015-01-01

In this large scale, individual differences study (N = 521), the effects of cardinal axes of an environment and the path taken between locations on distance comparisons were assessed. The main goal was to identify if and to what extent previous findings in simple 2D tasks can be generalized to a more dynamic, three-dimensional virtual reality environment. Moreover, effects of age and gender were assessed. After memorizing the locations of six objects in a circular environment, participants were asked to judge the distance between objects they encountered. Results indicate that categorization (based on the cardinal axes) was present, as distances within one quadrant were judged as being closer together, even when no visual indication of the cardinal axes was given. Moreover, strong effects of the path taken between object locations were found; objects that were near on the path taken were perceived as being closer together than objects that were further apart on this path, regardless of the metric distance between the objects. Males outperformed females in distance comparison, but did not differ in the extent of the categorization and path effects. Age also affected performance; the categorization and path effects were highly similar across the age range tested, but the general ability to estimate distances does show a clear pattern increase during development and decrease with aging. PMID:26321968

Enhancing Convective Heat Transfer over a Surrogate Photovoltaic Panel

NASA Astrophysics Data System (ADS)

Fouladi, Fama

This research is particularly focused on studying heat transfer enhancement of a photovoltaic (PV) panel by putting an obstacle at the panel's windward edge. The heat transfer enhancement is performed by disturbing the airflow over the surface and increasing the heat and momentum transfer. Different objects such as triangular, square, rectangular, and discrete rectangular ribs and partial grids were applied at the leading edge of a surrogate PV panel and flow and the heat transfer of the panel are investigated experimentally. This approach was selected to expand understanding of effect of these different objects on the flow and turbulence structures over a flat surface by analyzing the flow comprehensively. It is observed that, a transverse object at the plate's leading edge would cause some flow blockage in the streamwise direction, but at the same time creates some velocity in the normal and cross stream directions. In addition to that, the obstacle generates some turbulence over the surface which persists for a long downstream distance. Also, among all studied objects, discrete rectangular ribs demonstrate the highest heat transfer rate enhancement (maximum Nu/Nu0 of 1.5). However, ribs with larger gap ratios are observed to be more effective at enhancing the heat transfer augmentation at closer distances to the rib, while at larger downstream distances from the rib, discrete ribs with smaller gap ratios are more effective. Furthermore, this work attempted to recognize the most influential flow parameters on the heat transfer enhancement of the surface. It is seen that the flow structure over a surface downstream of an object (flow separation-reattachment behaviour) has a significant effect on the heat transfer enhancement trend. Also, turbulence intensities are the most dominant parameters in enhancing the heat transfer rate from the surface; however, flow velocity (mostly normal velocity) is also an important factor.

Sex differences present in auditory looming perception, absent in auditory recession

NASA Astrophysics Data System (ADS)

Neuhoff, John G.; Seifritz, Erich

2005-04-01

When predicting the arrival time of an approaching sound source, listeners typically exhibit an anticipatory bias that affords a margin of safety in dealing with looming objects. The looming bias has been demonstrated behaviorally in the laboratory and in the field (Neuhoff 1998, 2001), neurally in fMRI studies (Seifritz et al., 2002), and comparatively in non-human primates (Ghazanfar, Neuhoff, and Logothetis, 2002). In the current work, male and female listeners were presented with three-dimensional looming sound sources and asked to press a button when the source was at the point of closest approach. Females exhibited a significantly greater anticipatory bias than males. Next, listeners were presented with sounds that either approached or receded and then stopped at three different terminal distances. Consistent with the time-to-arrival judgments, female terminal distance judgments for looming sources were significantly closer than male judgments. However, there was no difference between male and female terminal distance judgments for receding sounds. Taken together with the converging behavioral, neural, and comparative evidence, the current results illustrate the environmental salience of looming sounds and suggest that the anticipatory bias for auditory looming may have been shaped by evolution to provide a selective advantage in dealing with looming objects.

Dynamical encoding of looming, receding, and focussing

NASA Astrophysics Data System (ADS)

Longtin, Andre; Clarke, Stephen Elisha; Maler, Leonard; CenterNeural Dynamics Collaboration

This talk will discuss a non-conventional neural coding task that may apply more broadly to many senses in higher vertebrates. We ask whether and how a non-visual sensory system can focus on an object. We present recent experimental and modeling work that shows how the early sensory circuitry of electric sense can perform such neuronal focusing that is manifested behaviorally. This sense is the main one used by weakly electric fish to navigate, locate prey and communicate in the murky waters of their natural habitat. We show that there is a distance at which the Fisher information of a neuron's response to a looming and receding object is maximized, and that this distance corresponds to a behaviorally relevant one chosen by these animals. Strikingly, this maximum occurs at a bifurcation between tonic firing and bursting. We further discuss how the invariance of this distance to signal attributes can arise, a process that first involves power-law spike frequency adaptation. The talk will also highlight the importance of expanding the classic dual neural encoding of contrast using ON and OFF cells in the context of looming and receding stimuli. The authors acknowledge support from CIHR and NSERC.

The Effects of Age and Set Size on the Fast Extraction of Egocentric Distance

PubMed Central

Gajewski, Daniel A.; Wallin, Courtney P.; Philbeck, John W.

2016-01-01

Angular direction is a source of information about the distance to floor-level objects that can be extracted from brief glimpses (near one's threshold for detection). Age and set size are two factors known to impact the viewing time needed to directionally localize an object, and these were posited to similarly govern the extraction of distance. The question here was whether viewing durations sufficient to support object detection (controlled for age and set size) would also be sufficient to support well-constrained judgments of distance. Regardless of viewing duration, distance judgments were more accurate (less biased towards underestimation) when multiple potential targets were presented, suggesting that the relative angular declinations between the objects are an additional source of useful information. Distance judgments were more precise with additional viewing time, but the benefit did not depend on set size and accuracy did not improve with longer viewing durations. The overall pattern suggests that distance can be efficiently derived from direction for floor-level objects. Controlling for age-related differences in the viewing time needed to support detection was sufficient to support distal localization but only when brief and longer glimpse trials were interspersed. Information extracted from longer glimpse trials presumably supported performance on subsequent trials when viewing time was more limited. This outcome suggests a particularly important role for prior visual experience in distance judgments for older observers. PMID:27398065

Object detection system using SPAD proximity detectors

NASA Astrophysics Data System (ADS)

Stark, Laurence; Raynor, Jeffrey M.; Henderson, Robert K.

2011-10-01

This paper presents an object detection system based upon the use of multiple single photon avalanche diode (SPAD) proximity sensors operating upon the time-of-flight (ToF) principle, whereby the co-ordinates of a target object in a coordinate system relative to the assembly are calculated. The system is similar to a touch screen system in form and operation except that the lack of requirement of a physical sensing surface provides a novel advantage over most existing touch screen technologies. The sensors are controlled by FPGA-based firmware and each proximity sensor in the system measures the range from the sensor to the target object. A software algorithm is implemented to calculate the x-y coordinates of the target object based on the distance measurements from at least two separate sensors and the known relative positions of these sensors. Existing proximity sensors were capable of determining the distance to an object with centimetric accuracy and were modified to obtain a wide field of view in the x-y axes with low beam angle in z in order to provide a detection area as large as possible. Design and implementation of the firmware, electronic hardware, mechanics and optics are covered in the paper. Possible future work would include characterisation with alternative designs of proximity sensors, as this is the component which determines the highest achievable accur1acy of the system.

Distance estimation and collision prediction for on-line robotic motion planning

NASA Technical Reports Server (NTRS)

Kyriakopoulos, K. J.; Saridis, G. N.

1992-01-01

An efficient method for computing the minimum distance and predicting collisions between moving objects is presented. This problem is incorporated into the framework of an in-line motion-planning algorithm to satisfy collision avoidance between a robot and moving objects modeled as convex polyhedra. In the beginning, the deterministic problem where the information about the objects is assumed to be certain is examined. L(1) or L(infinity) norms are used to represent distance and the problem becomes a linear programming problem. The stochastic problem is formulated where the uncertainty is induced by sensing and the unknown dynamics of the moving obstacles. Two problems are considered: First, filtering of the distance between the robot and the moving object at the present time. Second, prediction of the minimum distance in the future in order to predict the collision time.

THE BOLOCAM GALACTIC PLANE SURVEY. VIII. A MID-INFRARED KINEMATIC DISTANCE DISCRIMINATION METHOD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellsworth-Bowers, Timothy P.; Glenn, Jason; Battersby, Cara

2013-06-10

We present a new distance estimation method for dust-continuum-identified molecular cloud clumps. Recent (sub-)millimeter Galactic plane surveys have cataloged tens of thousands of these objects, plausible precursors to stellar clusters, but detailed study of their physical properties requires robust distance determinations. We derive Bayesian distance probability density functions (DPDFs) for 770 objects from the Bolocam Galactic Plane Survey in the Galactic longitude range 7. Degree-Sign 5 {<=} l {<=} 65 Degree-Sign . The DPDF formalism is based on kinematic distances, and uses any number of external data sets to place prior distance probabilities to resolve the kinematic distance ambiguity (KDA)more » for objects in the inner Galaxy. We present here priors related to the mid-infrared absorption of dust in dense molecular regions and the distribution of molecular gas in the Galactic disk. By assuming a numerical model of Galactic mid-infrared emission and simple radiative transfer, we match the morphology of (sub-)millimeter thermal dust emission with mid-infrared absorption to compute a prior DPDF for distance discrimination. Selecting objects first from (sub-)millimeter source catalogs avoids a bias towards the darkest infrared dark clouds (IRDCs) and extends the range of heliocentric distance probed by mid-infrared extinction and includes lower-contrast sources. We derive well-constrained KDA resolutions for 618 molecular cloud clumps, with approximately 15% placed at or beyond the tangent distance. Objects with mid-infrared contrast sufficient to be cataloged as IRDCs are generally placed at the near kinematic distance. Distance comparisons with Galactic Ring Survey KDA resolutions yield a 92% agreement. A face-on view of the Milky Way using resolved distances reveals sections of the Sagittarius and Scutum-Centaurus Arms. This KDA-resolution method for large catalogs of sources through the combination of (sub-)millimeter and mid-infrared observations of molecular cloud clumps is generally applicable to other dust-continuum Galactic plane surveys.« less

VizieR Online Data Catalog: MIR view of polar dust emission in local AGNs (Asmus+, 2016)

NASA Astrophysics Data System (ADS)

Asmus, D.; Honig, S. F.; Gandhi, P.

2018-02-01

The parent sample for this work is the AGN MIR atlas of 253 objects (Asmus et al. 2014, J/MNRAS/439/1648). The optical classifications and distances (using the same cosmology) are adopted from that work. We furthermore use the nuclear MIR flux measurements from Asmus et al. (2014, J/MNRAS/439/1648). These are extracted from ground-based multi-filter photometry obtained with the instruments VLT/VISIR (Lagage et al. 2004Msngr.117...12L), Gemini/T-ReCS (Telesco et al. 1998SPIE.3354..534T), Gemini/Michelle (Glasse et al. 1997SPIE.2871.1197G), and Subaru/COMICS (Kataza et al. 2000SPIE.4008.1144K), with an angular resolution of the order of 0.35" or 120 pc for the median sample distance of 72 Mpc at 12 μm. (2 data files).

Pushing and pulling in relation to musculoskeletal disorders: a review of risk factors.

PubMed

Hoozemans, M J; van der Beek, A J; Frings-Dresen, M H; van Dijk, F J; van der Woude, L H

1998-06-01

The objective was to review the literature on risk factors for musculoskeletal disorders related to pushing and pulling. The risk factors have been described and evaluated from four perspectives: epidemiology, psychophysics, physiology, and biomechanics. Epidemiological studies have shown, based on cross-sectional data, that pushing and pulling is associated with low back pain. Evidence with respect to complaints of other parts of the musculoskeletal system is lacking. Risk factors have been found to influence the maximum (acceptable) push or pull forces as well as the physiological and mechanical strain on the human body. The risk factors have been divided into: (a) work situation, such as distance, frequency, handle height, and cart weight, (b) actual working method and posture/movement/exerted forces, such as foot distance and velocity, and (c) worker's characteristics, such as body weight. Longitudinal epidemiological studies are needed to relate pushing and pulling to musculoskeletal disorders.

Measuring Distances to Remote Galaxies and Quasars.

ERIC Educational Resources Information Center

McCarthy, Patrick J.

1988-01-01

Describes the use of spectroscopy and the redshift to measure how far an object is by measuring how fast it is receding from earth. Lists the most distant quasars yet found. Tables include "Redshift vs. Distance" and "Distances to Celestial Objects for Various Cosmologies." (CW)

Gravitational acceleration as a cue for absolute size and distance?

NASA Technical Reports Server (NTRS)

Hecht, H.; Kaiser, M. K.; Banks, M. S.

1996-01-01

When an object's motion is influenced by gravity, as in the rise and fall of a thrown ball, the vertical component of acceleration is roughly constant at 9.8 m/sec2. In principle, an observer could use this information to estimate the absolute size and distance of the object (Saxberg, 1987a; Watson, Banks, von Hofsten, & Royden, 1992). In five experiments, we examined people's ability to utilize the size and distance information provided by gravitational acceleration. Observers viewed computer simulations of an object rising and falling on a trajectory aligned with the gravitational vector. The simulated objects were balls of different diameters presented across a wide range of simulated distances. Observers were asked to identify the ball that was presented and to estimate its distance. The results showed that observers were much more sensitive to average velocity than to the gravitational acceleration pattern. Likewise, verticality of the motion and visibility of the trajectory's apex had negligible effects on the accuracy of size and distance judgments.

Modern Geometric Methods of Distance Determination

NASA Astrophysics Data System (ADS)

Thévenin, Frédéric; Falanga, Maurizio; Kuo, Cheng Yu; Pietrzyński, Grzegorz; Yamaguchi, Masaki

2017-11-01

Building a 3D picture of the Universe at any distance is one of the major challenges in astronomy, from the nearby Solar System to distant Quasars and galaxies. This goal has forced astronomers to develop techniques to estimate or to measure the distance of point sources on the sky. While most distance estimates used since the beginning of the 20th century are based on our understanding of the physics of objects of the Universe: stars, galaxies, QSOs, the direct measures of distances are based on the geometric methods as developed in ancient Greece: the parallax, which has been applied to stars for the first time in the mid-19th century. In this review, different techniques of geometrical astrometry applied to various stellar and cosmological (Megamaser) objects are presented. They consist in parallax measurements from ground based equipment or from space missions, but also in the study of binary stars or, as we shall see, of binary systems in distant extragalactic sources using radio telescopes. The Gaia mission will be presented in the context of stellar physics and galactic structure, because this key space mission in astronomy will bring a breakthrough in our understanding of stars, galaxies and the Universe in their nature and evolution with time. Measuring the distance to a star is the starting point for an unbiased description of its physics and the estimate of its fundamental parameters like its age. Applying these studies to candles such as the Cepheids will impact our large distance studies and calibration of other candles. The text is constructed as follows: introducing the parallax concept and measurement, we shall present briefly the Gaia satellite which will be the future base catalogue of stellar astronomy in the near future. Cepheids will be discussed just after to demonstrate the state of the art in distance measurements in the Universe with these variable stars, with the objective of 1% of error in distances that could be applied to our closest galaxy the LMC, and better constrain the distances of large sub-structures around the Milky Way. Then exciting objects like X-Ray binaries will be presented in two parts corresponding to "low" or "high" mass stars with compact objects observed with X-ray satellites. We shall demonstrate the capability of these objects to have their distances measured with high accuracy with not only helps in the study of these objects but could also help to measure the distance of the structure they belong. For cosmological objects and large distances of megaparsecs, we shall present what has been developed for more than 20 years in the geometric distance measurements of MegaMasers, the ultimate goal being the estimation of the H0 parameter.

Zoom microscope objective using electrowetting lenses.

PubMed

Li, Lei; Wang, Di; Liu, Chao; Wang, Qiong-Hua

2016-02-08

We report a zoom microscope objective which can achieve continuous zoom change and correct the aberrations dynamically. The objective consists of three electrowetting liquid lenses and two glass lenses. The magnification is changed by applying voltages on the three electrowetting lenses. Besides, the three electrowetting liquid lenses can play a role to correct the aberrations. A digital microscope based on the proposed objective is demonstrated. We analyzed the properties of the proposed objective. In contrast to the conventional objectives, the proposed objective can be tuned from ~7.8 × to ~13.2 × continuously. For our objective, the working distance is fixed, which means no movement parts are needed to refocus or change its magnification. Moreover, the zoom objective can be dynamically optimized for a wide range of wavelength. Using such an objective, the fabrication tolerance of the optical system is larger than that of a conventional system, which can decrease the fabrication cost. The proposed zoom microscope objective cannot only take place of the conventional objective, but also has potential application in the 3D microscopy.

The traveling salesman problem in surgery: economy of motion for the FLS Peg Transfer task.

PubMed

Falcone, John L; Chen, Xiaotian; Hamad, Giselle G

2013-05-01

In the Peg Transfer task in the Fundamentals of Laparoscopic Surgery (FLS) curriculum, six peg objects are sequentially transferred in a bimanual fashion using laparoscopic instruments across a pegboard and back. There are over 268 trillion ways of completing this task. In the setting of many possibilities, the traveling salesman problem is one where the objective is to solve for the shortest distance traveled through a fixed number of points. The goal of this study is to apply the traveling salesman problem to find the shortest two-dimensional path length for this task. A database platform was used with permutation application output to generate all of the single-direction solutions of the FLS Peg Transfer task. A brute-force search was performed using nested Boolean operators and database equations to calculate the overall two-dimensional distances for the efficient and inefficient solutions. The solutions were found by evaluating peg object transfer distances and distances between transfers for the nondominant and dominant hands. For the 518,400 unique single-direction permutations, the mean total two-dimensional peg object travel distance was 33.3 ± 1.4 cm. The range in distances was from 30.3 to 36.5 cm. There were 1,440 (0.28 %) of 518,400 efficient solutions with the minimized peg object travel distance of 30.3 cm. There were 8 (0.0015 %) of 518,400 solutions in the final solution set that minimized the distance of peg object transfer and minimized the distance traveled between peg transfers. Peg objects moved 12.7 cm (17.4 %) less in the efficient solutions compared to the inefficient solutions. The traveling salesman problem can be applied to find efficient solutions for surgical tasks. The eight solutions to the FLS Peg Transfer task are important for any examinee taking the FLS curriculum and for certification by the American Board of Surgery.

Phase contrast imaging simulation and measurements using polychromatic sources with small source-object distances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golosio, Bruno; Carpinelli, Massimo; Masala, Giovanni Luca

Phase contrast imaging is a technique widely used in synchrotron facilities for nondestructive analysis. Such technique can also be implemented through microfocus x-ray tube systems. Recently, a relatively new type of compact, quasimonochromatic x-ray sources based on Compton backscattering has been proposed for phase contrast imaging applications. In order to plan a phase contrast imaging system setup, to evaluate the system performance and to choose the experimental parameters that optimize the image quality, it is important to have reliable software for phase contrast imaging simulation. Several software tools have been developed and tested against experimental measurements at synchrotron facilities devotedmore » to phase contrast imaging. However, many approximations that are valid in such conditions (e.g., large source-object distance, small transverse size of the object, plane wave approximation, monochromatic beam, and Gaussian-shaped source focal spot) are not generally suitable for x-ray tubes and other compact systems. In this work we describe a general method for the simulation of phase contrast imaging using polychromatic sources based on a spherical wave description of the beam and on a double-Gaussian model of the source focal spot, we discuss the validity of some possible approximations, and we test the simulations against experimental measurements using a microfocus x-ray tube on three types of polymers (nylon, poly-ethylene-terephthalate, and poly-methyl-methacrylate) at varying source-object distance. It will be shown that, as long as all experimental conditions are described accurately in the simulations, the described method yields results that are in good agreement with experimental measurements.« less

Object Detection for Agricultural and Construction Environments Using an Ultrasonic Sensor.

PubMed

Dvorak, J S; Stone, M L; Self, K P

2016-04-01

This study tested an ultrasonic sensor's ability to detect several objects commonly encountered in outdoor agricultural or construction environments: a water jug, a sheet of oriented strand board (OSB), a metalfence post, a human model, a wooden fence post, a Dracaena plant, a juniper plant, and a dog model. Tests were performed with each target object at distances from 0.01 to 3 m. Five tests were performed with each object at each location, and the sensor's ability to detect the object during each test was categorized as "undetected," "intermittent," "incorrect distance," or "good." Rigid objects that presented a larger surface area to the sensor, such as the water jug and OSB, were better detected than objects with a softer surface texture, which were occasionally not detected as the distance approached 3 m. Objects with extremely soft surface texture, such as the dog model, could be undetected at almost any distance from the sensor. The results of this testing should help designers offuture systems for outdoor environments, as the target objects tested can be found in nearly any agricultural or construction environment.

Distance-Dependent Processing of Pictures and Words

ERIC Educational Resources Information Center

Amit, Elinor; Algom, Daniel; Trope, Yaacov

2009-01-01

A series of 8 experiments investigated the association between pictorial and verbal representations and the psychological distance of the referent objects from the observer. The results showed that people better process pictures that represent proximal objects and words that represent distal objects than pictures that represent distal objects and…

Directional Unfolded Source Term (DUST) for Compton Cameras.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Dean J.; Horne, Steven M.; O'Brien, Sean

2018-03-01

A Directional Unfolded Source Term (DUST) algorithm was developed to enable improved spectral analysis capabilities using data collected by Compton cameras. Achieving this objective required modification of the detector response function in the Gamma Detector Response and Analysis Software (GADRAS). Experimental data that were collected in support of this work include measurements of calibration sources at a range of separation distances and cylindrical depleted uranium castings.

Debris perturbed by radiation pressure: relative velocities across circular orbits

NASA Astrophysics Data System (ADS)

Celestino, C.; Winter, O.; Prado, A.

It is widely know that there is a large amount of space debris and meteoroid particles around the Earth. The objects larger than 10 cm can be tracked by radar and others means allowing the satellites/ships to be maneuvered to avoid collisions. However, the detection and the attendance of the orbital dynamics of objects smaller than 10 cm (particles) is very difficult. These particles can be generated by explosions of larger objects, collisions between large objects, or simply for the reaction of the oxygen in the wall of an object could generate the escape of paint pieces. The importance of studying the dynamics of these particles is that they can have relative high speeds and their effects in a collision could cause damages and even compromise the space missions. In this present work we considered a dynamical system of mm size particles around the Earth subject to the effects of radiation pressure. Our main goal is to study the evolution of its relative velocity to the circular orbits that it crosses.Firstly, it is considered that the particle is initially in circular orbit. The effect of the radiation pressure produces variations in its eccentricity, resulting in a change in its orbital velocity. The results show that the variation of the radial distance and the relative velocity can be divided in three parts: secular, long period and short period. For the radial distance the secular variation is constant, because the semi-axis is constant. The long period variation presents a configuration that repeats with period inferior to the orbital period of the Earth. And, finally, the short period variation presents points of local maxima and minima for the variation of the width of the radial distance. When considering the variation of the relative velocity we have that the secular behavior and of long period are similar to those obtained for the variation of the radial distance. However, for the short period variation, we have a larger number of local maxima and minima in comparison to the radial distance. The relative velocity for particles initially geostationary of size 5,0 mm are around 4,0 km/s. Acknowledgments: The authors thank FAPESP, CNPq and FUNDUNESP for the financial support.

[An experimental study of effects of active-heating-system for extravehicular spacesuit gloves on working performance].

PubMed

Ding, Li; Han, Long-zhu; Yang, Chun-xin; Yang, Feng; Yuan, Xiu-gan

2005-02-01

To observe the effects of active heating system for spacesuit gloves on extravehicular working performance. After analyzing the factors with gloves influence on the working performance, the effects of active heating system for gloves were studied experimentally with aspects to fatigue, hand strength, dexterity and tactile sensing. 1) Heating-system had not influence to grip; 2) Heating-system had 17% influence to fatigue except specific person; 3) Nut assembly and nipping pin showed that heating-system had little influence to dexterity; 4) Apperceiving shape of object and two-point distance showed heating-system had little influence to tactility. The active heating method is rational and has little influence on working performance.

Distance estimation and collision prediction for on-line robotic motion planning

NASA Technical Reports Server (NTRS)

Kyriakopoulos, K. J.; Saridis, G. N.

1991-01-01

An efficient method for computing the minimum distance and predicting collisions between moving objects is presented. This problem has been incorporated in the framework of an in-line motion planning algorithm to satisfy collision avoidance between a robot and moving objects modeled as convex polyhedra. In the beginning the deterministic problem, where the information about the objects is assumed to be certain is examined. If instead of the Euclidean norm, L(sub 1) or L(sub infinity) norms are used to represent distance, the problem becomes a linear programming problem. The stochastic problem is formulated, where the uncertainty is induced by sensing and the unknown dynamics of the moving obstacles. Two problems are considered: (1) filtering of the minimum distance between the robot and the moving object, at the present time; and (2) prediction of the minimum distance in the future, in order to predict possible collisions with the moving obstacles and estimate the collision time.

Systems and Methods for Locating a Target in a GPS-Denied Environment

NASA Technical Reports Server (NTRS)

Mackay, John D. (Inventor); Murdock, Ronald G. (Inventor); Cummins, Douglas A. (Inventor)

2017-01-01

A system for locating an object in a GPS-denied environment includes first and second stationary nodes of a network and an object out of synchronization with a common time base of the network. The system includes one or more processors that are configured to estimate distances between the first stationary node and the object and a distance between the second stationary node and the object by comparing time-stamps of messages relayed between the object and the nodes. A position of the object can then be trilaterated using a location of each of the first and second stationary nodes and the measured distances between the object and each of the first and second stationary nodes.

A new statistical distance scale for planetary nebulae

NASA Astrophysics Data System (ADS)

Ali, Alaa; Ismail, H. A.; Alsolami, Z.

2015-05-01

In the first part of the present article we discuss the consistency among different individual distance methods of Galactic planetary nebulae, while in the second part we develop a new statistical distance scale based on a calibrating sample of well determined distances. A set composed of 315 planetary nebulae with individual distances are extracted from the literature. Inspecting the data set indicates that the accuracy of distances is varying among different individual methods and also among different sources where the same individual method was applied. Therefore, we derive a reliable weighted mean distance for each object by considering the influence of the distance error and the weight of each individual method. The results reveal that the discussed individual methods are consistent with each other, except the gravity method that produces higher distances compared to other individual methods. From the initial data set, we construct a standard calibrating sample consists of 82 objects. This sample is restricted only to the objects with distances determined from at least two different individual methods, except few objects with trusted distances determined from the trigonometric, spectroscopic, and cluster membership methods. In addition to the well determined distances for this sample, it shows a lot of advantages over that used in the prior distance scales. This sample is used to recalibrate the mass-radius and radio surface brightness temperature-radius relationships. An average error of ˜30 % is estimated for the new distance scale. The newly distance scale is compared with the most widely used statistical scales in literature, where the results show that it is roughly similar to the majority of them within ˜±20 % difference. Furthermore, the new scale yields a weighted mean distance to the Galactic center of 7.6±1.35 kpc, which in good agreement with the very recent measure of Malkin 2013.

Fine-grained, local maps and coarse, global representations support human spatial working memory.

PubMed

Katshu, Mohammad Zia Ul Haq; d'Avossa, Giovanni

2014-01-01

While sensory processes are tuned to particular features, such as an object's specific location, color or orientation, visual working memory (vWM) is assumed to store information using representations, which generalize over a feature dimension. Additionally, current vWM models presume that different features or objects are stored independently. On the other hand, configurational effects, when observed, are supposed to mainly reflect encoding strategies. We show that the location of the target, relative to the display center and boundaries, and overall memory load influenced recall precision, indicating that, like sensory processes, capacity limited vWM resources are spatially tuned. When recalling one of three memory items the target distance from the display center was overestimated, similar to the error when only one item was memorized, but its distance from the memory items' average position was underestimated, showing that not only individual memory items' position, but also the global configuration of the memory array may be stored. Finally, presenting the non-target items at recall, consequently providing landmarks and configurational information, improved precision and accuracy of target recall. Similarly, when the non-target items were translated at recall, relative to their position in the initial display, a parallel displacement of the recalled target was observed. These findings suggest that fine-grained spatial information in vWM is represented in local maps whose resolution varies with distance from landmarks, such as the display center, while coarse representations are used to store the memory array configuration. Both these representations are updated at the time of recall.

Fine-Grained, Local Maps and Coarse, Global Representations Support Human Spatial Working Memory

PubMed Central

Katshu, Mohammad Zia Ul Haq; d'Avossa, Giovanni

2014-01-01

While sensory processes are tuned to particular features, such as an object's specific location, color or orientation, visual working memory (vWM) is assumed to store information using representations, which generalize over a feature dimension. Additionally, current vWM models presume that different features or objects are stored independently. On the other hand, configurational effects, when observed, are supposed to mainly reflect encoding strategies. We show that the location of the target, relative to the display center and boundaries, and overall memory load influenced recall precision, indicating that, like sensory processes, capacity limited vWM resources are spatially tuned. When recalling one of three memory items the target distance from the display center was overestimated, similar to the error when only one item was memorized, but its distance from the memory items' average position was underestimated, showing that not only individual memory items' position, but also the global configuration of the memory array may be stored. Finally, presenting the non-target items at recall, consequently providing landmarks and configurational information, improved precision and accuracy of target recall. Similarly, when the non-target items were translated at recall, relative to their position in the initial display, a parallel displacement of the recalled target was observed. These findings suggest that fine-grained spatial information in vWM is represented in local maps whose resolution varies with distance from landmarks, such as the display center, while coarse representations are used to store the memory array configuration. Both these representations are updated at the time of recall. PMID:25259601

Purple sea urchin Strongylocentrotus purpuratus gamete manipulation using optical trapping and microfluidics

NASA Astrophysics Data System (ADS)

Chandsawangbhuwana, Charlie; Shi, Linda Z.; Zhu, Qingyuan; Berns, Michael W.

2013-04-01

A system has been developed that allows for optical and fluidic manipulation of gametes. The optical manipulation is performed by using a single-point gradient trap with a 40× oil immersion PH3 1.3 NA objective on a Zeiss inverted microscope. The fluidic manipulation is performed by using a custom microfluidic chamber designed to fit into the short working distance between the condenser and objective. The system is validated using purple sea urchin Strongylocentrotus purpuratus gametes and has the potential to be used for mammalian in vitro fertilization and animal husbandry.

The contribution of distance education to health promotion in Chile.

PubMed

Salinas, Judith; Muñoz, Carolina; Albagli, Andrea; Araya, Gloria; Vio, Fernando

2017-10-01

The objective of this paper is to present the distance education's contribution to developing health promotion in Chile, through evaluation of a postgraduate certificate program for professionals, and a training course for nurse technicians working in primary healthcare, with an 8-month follow-up after program completion. The program methodology was participatory, interactive and reflective, with mentoring support, exercises, group work and discussions as well as content pertinent to the needs of practice. The evaluation was quali-quantitative with an analysis of the student profile, the implementation process, outcomes at the end of the training and impacts on workplace changes. The results showed a high rate of student approval (87 and 76%), good academic performance and a high level of satisfaction with the methodology and knowledge delivered. The participants' final projects were adapted to local work places realities and were implemented by 62.6% of technicians and 43% of professionals, in addition to changes in work practices that favor health promotion. The level of fulfillment of participants' expectations was very high and the most frequent barriers to implementing the final project were lack of time and personnel, along with minimal support from management and low prioritization of health promotion. This study shows the effectiveness of a distance training model for professionals and technicians that can reach the most remote parts of the country, where there is no access to presencial training, with an educational program centered on work activities and current health challenges. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quickly Approximating the Distance Between Two Objects

NASA Technical Reports Server (NTRS)

Hammen, David

2009-01-01

A method of quickly approximating the distance between two objects (one smaller, regarded as a point; the other larger and complexly shaped) has been devised for use in computationally simulating motions of the objects for the purpose of planning the motions to prevent collisions.

Using the Bootstrap Method for a Statistical Significance Test of Differences between Summary Histograms

NASA Technical Reports Server (NTRS)

Xu, Kuan-Man

2006-01-01

A new method is proposed to compare statistical differences between summary histograms, which are the histograms summed over a large ensemble of individual histograms. It consists of choosing a distance statistic for measuring the difference between summary histograms and using a bootstrap procedure to calculate the statistical significance level. Bootstrapping is an approach to statistical inference that makes few assumptions about the underlying probability distribution that describes the data. Three distance statistics are compared in this study. They are the Euclidean distance, the Jeffries-Matusita distance and the Kuiper distance. The data used in testing the bootstrap method are satellite measurements of cloud systems called cloud objects. Each cloud object is defined as a contiguous region/patch composed of individual footprints or fields of view. A histogram of measured values over footprints is generated for each parameter of each cloud object and then summary histograms are accumulated over all individual histograms in a given cloud-object size category. The results of statistical hypothesis tests using all three distances as test statistics are generally similar, indicating the validity of the proposed method. The Euclidean distance is determined to be most suitable after comparing the statistical tests of several parameters with distinct probability distributions among three cloud-object size categories. Impacts on the statistical significance levels resulting from differences in the total lengths of satellite footprint data between two size categories are also discussed.

Task-specific modulation of adult humans' tool preferences: number of choices and size of the problem.

PubMed

Silva, Kathleen M; Gross, Thomas J; Silva, Francisco J

2015-03-01

In two experiments, we examined the effect of modifications to the features of a stick-and-tube problem on the stick lengths that adult humans used to solve the problem. In Experiment 1, we examined whether people's tool preferences for retrieving an out-of-reach object in a tube might more closely resemble those reported with laboratory crows if people could modify a single stick to an ideal length to solve the problem. Contrary to when adult humans have selected a tool from a set of ten sticks, asking people to modify a single stick to retrieve an object did not generally result in a stick whose length was related to the object's distance. Consistent with the prior research, though, the working length of the stick was related to the object's distance. In Experiment 2, we examined the effect of increasing the scale of the stick-and-tube problem on people's tool preferences. Increasing the scale of the task influenced people to select relatively shorter tools than had selected in previous studies. Although the causal structures of the tasks used in the two experiments were identical, their results were not. This underscores the necessity of studying physical cognition in relation to a particular causal structure by using a variety of tasks and methods.

Construal-Level Theory of Psychological Distance

PubMed Central

Trope, Yaacov; Liberman, Nira

2011-01-01

People are capable of thinking about the future, the past, remote locations, another person’s perspective, and counterfactual alternatives. Without denying the uniqueness of each process, it is proposed that they constitute different forms of traversing psychological distance. Psychological distance is egocentric: Its reference point is the self in the here and now, and the different ways in which an object might be removed from that point—in time, in space, in social distance, and in hypotheticality—constitute different distance dimensions. Transcending the self in the here and now entails mental construal, and the farther removed an object is from direct experience, the higher (more abstract) the level of construal of that object. Supporting this analysis, research shows (a) that the various distances are cognitively related to each other, (b) that they similarly influence and are influenced by level of mental construal, and (c) that they similarly affect prediction, preference, and action. PMID:20438233

Change Detection of High-Resolution Remote Sensing Images Based on Adaptive Fusion of Multiple Features

NASA Astrophysics Data System (ADS)

Wang, G. H.; Wang, H. B.; Fan, W. F.; Liu, Y.; Chen, C.

2018-04-01

In view of the traditional change detection algorithm mainly depends on the spectral information image spot, failed to effectively mining and fusion of multi-image feature detection advantage, the article borrows the ideas of object oriented analysis proposed a multi feature fusion of remote sensing image change detection algorithm. First by the multi-scale segmentation of image objects based; then calculate the various objects of color histogram and linear gradient histogram; utilizes the color distance and edge line feature distance between EMD statistical operator in different periods of the object, using the adaptive weighted method, the color feature distance and edge in a straight line distance of combination is constructed object heterogeneity. Finally, the curvature histogram analysis image spot change detection results. The experimental results show that the method can fully fuse the color and edge line features, thus improving the accuracy of the change detection.

Tachistoscopic illumination and masking of real scenes.

PubMed

Chichka, David; Philbeck, John W; Gajewski, Daniel A

2015-03-01

Tachistoscopic presentation of scenes has been valuable for studying the emerging properties of visual scene representations. The spatial aspects of this work have generally been focused on the conceptual locations (e.g., next to the refrigerator) and directional locations of objects in 2-D arrays and/or images. Less is known about how the perceived egocentric distance of objects develops. Here we describe a novel system for presenting brief glimpses of a real-world environment, followed by a mask. The system includes projectors with mechanical shutters for projecting the fixation and masking images, a set of LED floodlights for illuminating the environment, and computer-controlled electronics to set the timing and initiate the process. Because a real environment is used, most visual distance and depth cues can be manipulated using traditional methods. The system is inexpensive, robust, and its components are readily available in the marketplace. This article describes the system and the timing characteristics of each component. We verified the system's ability to control exposure to time scales as low as a few milliseconds.

From static electric images to electric flow: towards dynamic perceptual cues in active electroreception.

PubMed

Hofmann, Volker; Sanguinetti-Scheck, Juan I; Gómez-Sena, Leonel; Engelmann, Jacob

2013-01-01

Active electroreception is an ancestral trait found in many aquatic vertebrates and has evolved independently in two teleost lineages, the Gymnotiformes and the Mormyriformes. Unique to these so-called weakly electric fish is their ability to actively generate electrical currents in the water and sense the electrical properties of the environment. How natural behavior contributes to this sensory system has been of interest to neuroethologists since the pioneering works of Lissmann. Here we report on a mutual modeling and experimental study of the stimuli available during active electrolocation of Gnathonemus petersii (Mormyridae). We show the validity of the model (I) by demonstrating that localized spatial patterns of object induced modulations in the electric field (electric images) are comparable to experimentally mapped 2-dimensional electric images and (II) by replicating earlier key findings showing that a normalized metric of electric image width provides an unambiguous cue for distance estimation. We then show that electric images and the distance metric vary systematically when an object is moved along the trunk. These potential ambiguities with regard to localization lead us to a spatiotemporal analysis of electric images. We introduce a new temporal metric for distance estimation that is based on the normalized spatial properties of electrical images. Finally, based on a survey of exploratory behavior, we show how objects situated at the tail, a region previously neglected, cast global electric images that extend over the whole sensory epithelium of the animals. Copyright © 2012 Elsevier Ltd. All rights reserved.

Directionally hiding objects and creating illusions above a carpet-like device by reflection holography

PubMed Central

Cheng, Qiluan; Wu, Kedi; Shi, Yile; Wang, Hui; Wang, Guo Ping

2015-01-01

Realization of a perfect invisibility cloak still challenges the current fabricating technologies. Most experiments, if not all, are hence focused on carpet cloaks because of their relatively low requirements to material properties. Nevertheless, present invisibility carpets are used to hide beneath objects. Here, we report a carpet-like device to directionally conceal objects and further to create illusions above it. The device is fabricated through recording a reflection hologram of objects and is used to produce a time-reversed signal to compensate for the information of the objects and further to create light field of another object so as to realize both functions of hiding the objects and creating illusions, respectively. The carpet-like device can work for macroscopic objects at visible wavelength as the distance between objects and device is at decimeter scale. Our carpet-like device to realizing invisibility and creating illusions may provide a robust way for crucial applications of magic camouflaging and anti-detection etc. PMID:25716451

Directionally hiding objects and creating illusions above a carpet-like device by reflection holography

NASA Astrophysics Data System (ADS)

Cheng, Qiluan; Wu, Kedi; Shi, Yile; Wang, Hui; Wang, Guo Ping

2015-02-01

Realization of a perfect invisibility cloak still challenges the current fabricating technologies. Most experiments, if not all, are hence focused on carpet cloaks because of their relatively low requirements to material properties. Nevertheless, present invisibility carpets are used to hide beneath objects. Here, we report a carpet-like device to directionally conceal objects and further to create illusions above it. The device is fabricated through recording a reflection hologram of objects and is used to produce a time-reversed signal to compensate for the information of the objects and further to create light field of another object so as to realize both functions of hiding the objects and creating illusions, respectively. The carpet-like device can work for macroscopic objects at visible wavelength as the distance between objects and device is at decimeter scale. Our carpet-like device to realizing invisibility and creating illusions may provide a robust way for crucial applications of magic camouflaging and anti-detection etc.

Supporting Dynamic Quantization for High-Dimensional Data Analytics.

PubMed

Guzun, Gheorghi; Canahuate, Guadalupe

2017-05-01

Similarity searches are at the heart of exploratory data analysis tasks. Distance metrics are typically used to characterize the similarity between data objects represented as feature vectors. However, when the dimensionality of the data increases and the number of features is large, traditional distance metrics fail to distinguish between the closest and furthest data points. Localized distance functions have been proposed as an alternative to traditional distance metrics. These functions only consider dimensions close to query to compute the distance/similarity. Furthermore, in order to enable interactive explorations of high-dimensional data, indexing support for ad-hoc queries is needed. In this work we set up to investigate whether bit-sliced indices can be used for exploratory analytics such as similarity searches and data clustering for high-dimensional big-data. We also propose a novel dynamic quantization called Query dependent Equi-Depth (QED) quantization and show its effectiveness on characterizing high-dimensional similarity. When applying QED we observe improvements in kNN classification accuracy over traditional distance functions. Gheorghi Guzun and Guadalupe Canahuate. 2017. Supporting Dynamic Quantization for High-Dimensional Data Analytics. In Proceedings of Ex-ploreDB'17, Chicago, IL, USA, May 14-19, 2017, 6 pages. https://doi.org/http://dx.doi.org/10.1145/3077331.3077336.

In-Situ Waviness Characterization of Metal Plates by a Lateral Shearing Interferometric Profilometer

PubMed Central

Frade, María; Enguita, José María; Álvarez, Ignacio

2013-01-01

Characterizing waviness in sheet metal is a key process for quality control in many industries, such as automotive and home appliance manufacturing. However, there is still no known technique able to work in an automated in-floor inspection system. The literature describes many techniques developed in the last three decades, but most of them are either slow, only able to work in laboratory conditions, need very short (unsafe) working distances, or are only able to estimate certain waviness parameters. In this article we propose the use of a lateral shearing interferometric profilometer, which is able to obtain a 19 mm profile in a single acquisition, with sub-micron precision, in an uncontrolled environment, and from a working distance greater than 90 mm. This system allows direct measurement of all needed waviness parameters even with objects in movement. We describe a series of experiments over several samples of steel plates to validate the sensor and the processing method, and the results are in close agreement with those obtained with a contact stylus device. The sensor is an ideal candidate for on-line or in-machine fast automatic waviness assessment, reducing delays and costs in many metalworking processes. PMID:23584120

In-situ waviness characterization of metal plates by a lateral shearing interferometric profilometer.

PubMed

Frade, María; Enguita, José María; Alvarez, Ignacio

2013-04-12

Characterizing waviness in sheet metal is a key process for quality control in many industries, such as automotive and home appliance manufacturing. However, there is still no known technique able to work in an automated in-floor inspection system. The literature describes many techniques developed in the last three decades, but most of them are either slow, only able to work in laboratory conditions, need very short (unsafe) working distances, or are only able to estimate certain waviness parameters. In this article we propose the use of a lateral shearing interferometric profilometer, which is able to obtain a 19 mm profile in a single acquisition, with sub-micron precision, in an uncontrolled environment, and from a working distance greater than 90 mm. This system allows direct measurement of all needed waviness parameters even with objects in movement. We describe a series of experiments over several samples of steel plates to validate the sensor and the processing method, and the results are in close agreement with those obtained with a contact stylus device. The sensor is an ideal candidate for on-line or in-machine fast automatic waviness assessment, reducing delays and costs in many metalworking processes.

Manually locating physical and virtual reality objects.

PubMed

Chen, Karen B; Kimmel, Ryan A; Bartholomew, Aaron; Ponto, Kevin; Gleicher, Michael L; Radwin, Robert G

2014-09-01

In this study, we compared how users locate physical and equivalent three-dimensional images of virtual objects in a cave automatic virtual environment (CAVE) using the hand to examine how human performance (accuracy, time, and approach) is affected by object size, location, and distance. Virtual reality (VR) offers the promise to flexibly simulate arbitrary environments for studying human performance. Previously, VR researchers primarily considered differences between virtual and physical distance estimation rather than reaching for close-up objects. Fourteen participants completed manual targeting tasks that involved reaching for corners on equivalent physical and virtual boxes of three different sizes. Predicted errors were calculated from a geometric model based on user interpupillary distance, eye location, distance from the eyes to the projector screen, and object. Users were 1.64 times less accurate (p < .001) and spent 1.49 times more time (p = .01) targeting virtual versus physical box corners using the hands. Predicted virtual targeting errors were on average 1.53 times (p < .05) greater than the observed errors for farther virtual targets but not significantly different for close-up virtual targets. Target size, location, and distance, in addition to binocular disparity, affected virtual object targeting inaccuracy. Observed virtual box inaccuracy was less than predicted for farther locations, suggesting possible influence of cues other than binocular vision. Human physical interaction with objects in VR for simulation, training, and prototyping involving reaching and manually handling virtual objects in a CAVE are more accurate than predicted when locating farther objects.

HEARING IMPAIRMENT AND HYPERTENSION AMONG LONG DISTANCE BUS DRIVERS

PubMed Central

Abdelmoneim, Ismail

2003-01-01

Objectives: To investigate the prevalence of possible hearing impairment and hypertension in long distance bus drivers compared to the city bus drivers in Abha city. Methods: This was a cross-sectional study involving 62 long distance bus drivers and 46 city bus drivers from October 2001 to March 2002. A specially-designed questionnaire was administered to the drivers to explore some of their socioeconomic backgrounds. A pure tone air conduction audiometry and blood pressure measurements were performed. Results: Long distance bus drivers’ workload is significantly higher than that of city drivers (total weekly hours 64.0±14.3 compared to 46.7±5.5). Hearing impairment was significantly more among long distance drivers in the frequencies of 250, 500, 1000 and 2000 Hz especially in the left ear even after age corrections. The prevalence of mild hearing loss and hypertension were also higher among the long distance drivers (19.4% vs 4.5% and 38.7% vs 13% respectively). Conclusion and recommendations: This study showed more hearing affection and a higher prevalence of hypertension among long distance bus drivers than their counterparts operating in the city. Their hearing acuity should be tested before they start work and regularly afterwards. The stresses and strains of the job should be further studied and relieved; and regular health checks including blood pressure monitoring are to be instituted. PMID:23012034

A Proposal for Automatic Fruit Harvesting by Combining a Low Cost Stereovision Camera and a Robotic Arm

PubMed Central

Font, Davinia; Pallejà, Tomàs; Tresanchez, Marcel; Runcan, David; Moreno, Javier; Martínez, Dani; Teixidó, Mercè; Palacín, Jordi

2014-01-01

This paper proposes the development of an automatic fruit harvesting system by combining a low cost stereovision camera and a robotic arm placed in the gripper tool. The stereovision camera is used to estimate the size, distance and position of the fruits whereas the robotic arm is used to mechanically pickup the fruits. The low cost stereovision system has been tested in laboratory conditions with a reference small object, an apple and a pear at 10 different intermediate distances from the camera. The average distance error was from 4% to 5%, and the average diameter error was up to 30% in the case of a small object and in a range from 2% to 6% in the case of a pear and an apple. The stereovision system has been attached to the gripper tool in order to obtain relative distance, orientation and size of the fruit. The harvesting stage requires the initial fruit location, the computation of the inverse kinematics of the robotic arm in order to place the gripper tool in front of the fruit, and a final pickup approach by iteratively adjusting the vertical and horizontal position of the gripper tool in a closed visual loop. The complete system has been tested in controlled laboratory conditions with uniform illumination applied to the fruits. As a future work, this system will be tested and improved in conventional outdoor farming conditions. PMID:24984059

A proposal for automatic fruit harvesting by combining a low cost stereovision camera and a robotic arm.

PubMed

Font, Davinia; Pallejà, Tomàs; Tresanchez, Marcel; Runcan, David; Moreno, Javier; Martínez, Dani; Teixidó, Mercè; Palacín, Jordi

2014-06-30

This paper proposes the development of an automatic fruit harvesting system by combining a low cost stereovision camera and a robotic arm placed in the gripper tool. The stereovision camera is used to estimate the size, distance and position of the fruits whereas the robotic arm is used to mechanically pickup the fruits. The low cost stereovision system has been tested in laboratory conditions with a reference small object, an apple and a pear at 10 different intermediate distances from the camera. The average distance error was from 4% to 5%, and the average diameter error was up to 30% in the case of a small object and in a range from 2% to 6% in the case of a pear and an apple. The stereovision system has been attached to the gripper tool in order to obtain relative distance, orientation and size of the fruit. The harvesting stage requires the initial fruit location, the computation of the inverse kinematics of the robotic arm in order to place the gripper tool in front of the fruit, and a final pickup approach by iteratively adjusting the vertical and horizontal position of the gripper tool in a closed visual loop. The complete system has been tested in controlled laboratory conditions with uniform illumination applied to the fruits. As a future work, this system will be tested and improved in conventional outdoor farming conditions.

Distance Training: How Innovative Organizations Are Using Technology To Maximize Learning and Meet Business Objectives. Jossey-Bass Business and Management Series.

ERIC Educational Resources Information Center

Schreiber, Deborah A.; Berge, Zane L.

This book contains 19 papers examining ways in which innovative organizations are using distance learning technology to maximize learning and meet business objectives. The following papers are included: "Preface" (Deborah A. Schreiber, Zane L. Berge); "Organizational Technology and Its Impact on Distance Training" (Deborah A.…

New Intensity Attenuation in Georgia

NASA Astrophysics Data System (ADS)

Tsereteli, N. S.; Varazanashvili, O.; Tibaldi, A.; Bonali, F.; Gogoladze, Z.; Kvavadze, N.; Kvedelidze, I.

2016-12-01

In seismic-prone zones, increase of urbanization and infrastructures in turn produces increase of seismic risk that is mainly related to: the level of seismic hazard itself, the seismic resistance of dwelling houses, and many other factors. The relevant objectives of the present work is to improve the regional seismic hazard maps of Georgia, by implementing state-of-the art probabilistic seismic hazard assessment techniques and outputs from recent national and international collaborations. Seismic zoning is the identification of zones of similar levels of earthquake hazard. With reference to seismic zoning by ground motion assessment, the shaking intensity essentially depends on i) regional seismicity, ii) attenuation of ground motion with distance, iii) local site effects on ground motion. In the last decade, seismic hazard assessment is presented in terms of Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), or other recorded parameters. But there are very limited strong motion dataset in Georgia. Furthermore, vulnerability of buildings still is estimated for intensity, and there are no information about correlation between the distribution of ground motion recorded parameters and damage. So, macroseimic Intensity is still a very important parameter for strong ground motion evaluation. In the present work, we calibrated intensity prediction equations (IPE) for the Georgian dataset based on about 78 reviewed earthquakes. Metadata for Intensity (MSK 64 scale) were constrained and predictionequations for various types of distance (epicentral and hypocentral distance, Joyner-Boore distance, closest distance to the fault rupture plane) were calibrated. Relations between intensity and PGA values were derived. For this we used hybrid-empirical ground motion equation derived for Georgia and run scenario earthquakes for events with macroseismic data.

SU-E-J-197: Investigation of Microsoft Kinect 2.0 Depth Resolution for Patient Motion Tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silverstein, E; Snyder, M

2015-06-15

Purpose: Investigate the use of the Kinect 2.0 for patient motion tracking during radiotherapy by studying spatial and depth resolution capabilities. Methods: Using code written in C#, depth map data was abstracted from the Kinect to create an initial depth map template indicative of the initial position of an object to be compared to the depth map of the object over time. To test this process, simple setup was created in which two objects were imaged: a 40 cm × 40 cm board covered in non reflective material and a 15 cm × 26 cm textbook with a slightly reflective,more » glossy cover. Each object, imaged and measured separately, was placed on a movable platform with object to camera distance measured. The object was then moved a specified amount to ascertain whether the Kinect’s depth camera would visualize the difference in position of the object. Results: Initial investigations have shown the Kinect depth resolution is dependent on the object to camera distance. Measurements indicate that movements as small as 1 mm can be visualized for objects as close as 50 cm away. This depth resolution decreases linearly with object to camera distance. At 4 m, the depth resolution had decreased to observe a minimum movement of 1 cm. Conclusion: The improved resolution and advanced hardware of the Kinect 2.0 allows for increase of depth resolution over the Kinect 1.0. Although obvious that the depth resolution should decrease with increasing distance from an object given the decrease in number of pixels representing said object, the depth resolution at large distances indicates its usefulness in a clinical setting.« less

Multiobjective Policy Analysis to Evaluate Air Quality Impacts of Oil and Gas Regulations

NASA Astrophysics Data System (ADS)

Alongi, M.; Kasprzyk, J. R.; Milford, J.; Ryan, J. N.; Estep, M.

2016-12-01

Unconventional oil and gas development (UOGD) using hydraulic fracturing and horizontal drilling has recently fostered an unprecedented acceleration in energy development. Regulations seek to protect the public health of communities in proximity to UOGD and the environmental quality of these regions, while maintaining economic benefits. One such regulation is the setback distance, which dictates the minimum distance between an oil and gas well and an occupied structure, such as a residential or commercial building, or an area of special concern. This presentation discusses a new policy analysis framework for UOGD regulations, using the Borg multiobjective evolutionary algorithm (MOEA) coupled with AERMOD, a regulatory air dispersion model. The initial results explore how setback distance and well density regulations could impact the number of wells that can be drilled, based on a set of performance objectives that model potential increases in benzene, a hazardous air pollutant that has been linked to cancer and other detrimental health effects. The simulation calculates daily benzene averages using meteorological data from Greeley, CO. An important aspect of this work is to define representative quantitative objectives that accurately capture salient characteristics of the pollutant time series. For example, our framework will characterize the maximum concentration found over the entire spatial domain and over the duration of the simulation. Frequency-based objectives will also be explored, such as the number of exceedances of the benchmark annual average benzene concentration corresponding to a given level of cancer risk. The multiobjective analysis can also be expanded to integrate other objectives that represent performance-based outcomes on UOGD such as energy development profits, increases in noise pollution and decreases in property value. This research represents one application of how MOEAs can be used to inform policymaking for environmental regulations.

Traversing psychological distance.

PubMed

Liberman, Nira; Trope, Yaacov

2014-07-01

Traversing psychological distance involves going beyond direct experience, and includes planning, perspective taking, and contemplating counterfactuals. Consistent with this view, temporal, spatial, and social distances as well as hypotheticality are associated, affect each other, and are inferred from one another. Moreover, traversing all distances involves the use of abstraction, which we define as forming a belief about the substitutability for a specific purpose of subjectively distinct objects. Indeed, across many instances of both abstraction and psychological distancing, more abstract constructs are used for more distal objects. Here, we describe the implications of this relation for prediction, choice, communication, negotiation, and self-control. We ask whether traversing distance is a general mental ability and whether distance should replace expectancy in expected-utility theories. Copyright © 2014 Elsevier Ltd. All rights reserved.

Detection and Tracking of Dynamic Objects by Using a Multirobot System: Application to Critical Infrastructures Surveillance

PubMed Central

Rodríguez-Canosa, Gonzalo; Giner, Jaime del Cerro; Barrientos, Antonio

2014-01-01

The detection and tracking of mobile objects (DATMO) is progressively gaining importance for security and surveillance applications. This article proposes a set of new algorithms and procedures for detecting and tracking mobile objects by robots that work collaboratively as part of a multirobot system. These surveillance algorithms are conceived of to work with data provided by long distance range sensors and are intended for highly reliable object detection in wide outdoor environments. Contrary to most common approaches, in which detection and tracking are done by an integrated procedure, the approach proposed here relies on a modular structure, in which detection and tracking are carried out independently, and the latter might accept input data from different detection algorithms. Two movement detection algorithms have been developed for the detection of dynamic objects by using both static and/or mobile robots. The solution to the overall problem is based on the use of a Kalman filter to predict the next state of each tracked object. Additionally, new tracking algorithms capable of combining dynamic objects lists coming from either one or various sources complete the solution. The complementary performance of the separated modular structure for detection and identification is evaluated and, finally, a selection of test examples discussed. PMID:24526305

Hard x-ray focusing optics for concealed object detection

NASA Astrophysics Data System (ADS)

Jannson, Tomasz; Gertsenshteyn, Michael

2006-05-01

In this paper, we discuss hard x-ray optics, in general, and lobster-eye focusing optics, in particular, for concealed object detection, at longer distances. The longer distance (~50m) scenario is important for Improvised Explosives Detection (IED), "seeing through walls," "seeing objects under ground," and related applications.

Modeling the long-term evolution of space debris

DOEpatents

Nikolaev, Sergei; De Vries, Willem H.; Henderson, John R.; Horsley, Matthew A.; Jiang, Ming; Levatin, Joanne L.; Olivier, Scot S.; Pertica, Alexander J.; Phillion, Donald W.; Springer, Harry K.

2017-03-07

A space object modeling system that models the evolution of space debris is provided. The modeling system simulates interaction of space objects at simulation times throughout a simulation period. The modeling system includes a propagator that calculates the position of each object at each simulation time based on orbital parameters. The modeling system also includes a collision detector that, for each pair of objects at each simulation time, performs a collision analysis. When the distance between objects satisfies a conjunction criterion, the modeling system calculates a local minimum distance between the pair of objects based on a curve fitting to identify a time of closest approach at the simulation times and calculating the position of the objects at the identified time. When the local minimum distance satisfies a collision criterion, the modeling system models the debris created by the collision of the pair of objects.

Distance-dependent processing of pictures and words.

PubMed

Amit, Elinor; Algom, Daniel; Trope, Yaacov

2009-08-01

A series of 8 experiments investigated the association between pictorial and verbal representations and the psychological distance of the referent objects from the observer. The results showed that people better process pictures that represent proximal objects and words that represent distal objects than pictures that represent distal objects and words that represent proximal objects. These results were obtained with various psychological distance dimensions (spatial, temporal, and social), different tasks (classification and categorization), and different measures (speed of processing and selective attention). The authors argue that differences in the processing of pictures and words emanate from the physical similarity of pictures, but not words, to the referents. Consequently, perceptual analysis is commonly applied to pictures but not to words. Pictures thus impart a sense of closeness to the referent objects and are preferably used to represent such objects, whereas words do not convey proximity and are preferably used to represent distal objects in space, time, and social perspective.

Mind the gap: the minimal detectable separation distance between two objects during active electrolocation.

PubMed

Fechler, K; Holtkamp, D; Neusel, G; Sanguinetti-Scheck, J I; Budelli, R; von der Emde, G

2012-12-01

In a food-rewarded two-alternative forced-choice procedure, it was determined how well the weakly electric elephantnose fish Gnathonemus petersii can sense gaps between two objects, some of which were placed in front of complex backgrounds. The results show that at close distances, G. petersii is able to detect gaps between two small metal cubes (2 cm × 2 cm × 2 cm) down to a width of c. 1·5 mm. When larger objects (3 cm × 3 cm × 3 cm) were used, gaps with a width of 2-3 mm could still be detected. Discrimination performance was better (c. 1 mm gap size) when the objects were placed in front of a moving background consisting of plastic stripes or plant leaves, indicating that movement in the environment plays an important role for object identification. In addition, the smallest gap size that could be detected at increasing distances was determined. A linear relationship between object distance and gap size existed. Minimal detectable gap sizes increased from c. 1·5 mm at a distance of 1 cm, to 20 mm at a distance of 7 cm. Measurements and simulations of the electric stimuli occurring during gap detection revealed that the electric images of two close objects influence each other and superimpose. A large gap of 20 mm between two objects induced two clearly separated peaks in the electric image, while a 2 mm gap caused just a slight indentation in the image. Therefore, the fusion of electric images limits spatial resolution during active electrolocation. Relative movements either between the fish and the objects or between object and background might improve spatial resolution by accentuating the fine details of the electric images. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Data Fusion for a Vision-Radiological System: a Statistical Calibration Algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Enqvist, Andreas; Koppal, Sanjeev; Riley, Phillip

2015-07-01

Presented here is a fusion system based on simple, low-cost computer vision and radiological sensors for tracking of multiple objects and identifying potential radiological materials being transported or shipped. The main focus of this work is the development of calibration algorithms for characterizing the fused sensor system as a single entity. There is an apparent need for correcting for a scene deviation from the basic inverse distance-squared law governing the detection rates even when evaluating system calibration algorithms. In particular, the computer vision system enables a map of distance-dependence of the sources being tracked, to which the time-dependent radiological datamore » can be incorporated by means of data fusion of the two sensors' output data. (authors)« less

Automated spectral classification and the GAIA project

NASA Technical Reports Server (NTRS)

Lasala, Jerry; Kurtz, Michael J.

1995-01-01

Two dimensional spectral types for each of the stars observed in the global astrometric interferometer for astrophysics (GAIA) mission would provide additional information for the galactic structure and stellar evolution studies, as well as helping in the identification of unusual objects and populations. The classification of the large quantity generated spectra requires that automated techniques are implemented. Approaches for the automatic classification are reviewed, and a metric-distance method is discussed. In tests, the metric-distance method produced spectral types with mean errors comparable to those of human classifiers working at similar resolution. Data and equipment requirements for an automated classification survey, are discussed. A program of auxiliary observations is proposed to yield spectral types and radial velocities for the GAIA-observed stars.

The Place of Multiple Intelligence in Achieving the Objectives and Goals of Open and Distance Learning Institutions: A Critical Analysis

ERIC Educational Resources Information Center

Ojo, Olugbenga David; Olakulehin, Felix Kayode

2006-01-01

This paper examined the nature of open and distance learning institutions as organizations where synergy of efforts of all personnel is required in order to achieve the aims and objectives of the institution. It explored the huge infrastructural and personnel requirements of distance learning institutions, especially at inception, and the…

Practical Method to Identify Orbital Anomaly as Breakup Event in the Geostationary Region

DTIC Science & Technology

2015-01-14

point ! Geocentric distance at the pinch point Table 4 summarizes the results of the origin identifications. One object labeled x15300 was...Table 4. The result of origin identification of the seven detected objects Object name Parent object Inclination vector Pinch point Geocentric distance...of the object. X-Y, X’-Y’, and R.A.-Dec. represent the Image Coordinate before rotating the CCD sensor, after rotation, and the Geocentric Inertial

A Tactical Database for the Low Cost Combat Direction System

DTIC Science & Technology

1990-12-01

another object. Track is a representation of some environmental phenomena converted into accurate estimates of geographical position with respect to...by the method CALCULATE RELATIVE POSITION. In order to obtain a better similarity of mehods , the methods OWNSHIP DISTANCE TO PIM, ESTIMATED TIME OF...this mechanism entails the risk that the user will lose all of the work that was done if conflicts are detected and the transaction cannot be committed

Depth-estimation-enabled compound eyes

NASA Astrophysics Data System (ADS)

Lee, Woong-Bi; Lee, Heung-No

2018-04-01

Most animals that have compound eyes determine object distances by using monocular cues, especially motion parallax. In artificial compound eye imaging systems inspired by natural compound eyes, object depths are typically estimated by measuring optic flow; however, this requires mechanical movement of the compound eyes or additional acquisition time. In this paper, we propose a method for estimating object depths in a monocular compound eye imaging system based on the computational compound eye (COMPU-EYE) framework. In the COMPU-EYE system, acceptance angles are considerably larger than interommatidial angles, causing overlap between the ommatidial receptive fields. In the proposed depth estimation technique, the disparities between these receptive fields are used to determine object distances. We demonstrate that the proposed depth estimation technique can estimate the distances of multiple objects.

Measurement of the Length of an Optical Trap

NASA Technical Reports Server (NTRS)

Wrbanek, Susan Y.

2010-01-01

NASA Glenn has been involved in developing optical trapping and optical micromanipulation techniques in order to develop a tool that can be used to probe, characterize, and assemble nano and microscale materials to create microscale sensors for harsh flight environments. In order to be able to assemble a sensor or probe candidate sensor material, it is useful to know how far an optical trap can reach; that is, the distance beyond/below the stable trapping point through which an object will be drawn into the optical trap. Typically, to measure the distance over which an optical trap would influence matter in a horizontal (perpendicular to beam propagation) direction, it was common to hold an object in one optical trap, place a second optical trap a known distance away, turn off the first optical trap, and note if the object was moved into the second trap when it was turned on. The disadvantage of this technique is that it only gives information of trap influence distance in horizontal (x y) directions. No information about the distance of the influence of the trap is gained in the direction of propagation of the beam (the z direction). A method was developed to use a time-of-flight technique to determine the length along the propagation direction of an optical trap beam over which an object may be drawn into the optical trap. Test objects (polystyrene microspheres) were held in an optical trap in a water-filled sample chamber and raised to a pre-determined position near the top of the sample chamber. Next, the test objects were released by blocking the optical trap beam. The test objects were allowed to fall through the water for predetermined periods of time, at the end of which the trapping beam was unblocked. It was noted whether or not the test object returned to the optical trap or continued to fall. This determination of the length of an optical trap's influence by this manner assumes that the test object falls through the water in the sample chamber at terminal velocity for the duration of its fall, so that the distance of trap influence can be computed simply by: d = VTt, where d is the trap length (or distance of trap reach), VT is the terminal velocity of the test object, and t is the time interval over which the object is allowed to fall.

Depth-resolved ballistic imaging in a low-depth-of-field optical Kerr gated imaging system

NASA Astrophysics Data System (ADS)

Zheng, Yipeng; Tan, Wenjiang; Si, Jinhai; Ren, YuHu; Xu, Shichao; Tong, Junyi; Hou, Xun

2016-09-01

We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. This imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.

Depth-resolved ballistic imaging in a low-depth-of-field optical Kerr gated imaging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Yipeng; Tan, Wenjiang, E-mail: tanwenjiang@mail.xjtu.edu.cn; Si, Jinhai

2016-09-07

We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. Thismore » imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.« less

The combined use of Building Information Modelling (BIM) and Unmanned Aerial Vehicle (UAV) technologies for the 3D illustration of the progress of works in infrastructure construction projects

NASA Astrophysics Data System (ADS)

Vacanas, Yiannis; Themistocleous, Kyriacos; Agapiou, Athos; Hadjimitsis, Diofantos

2016-08-01

Building Information Modelling (BIM) technology is already part of the construction industry and is considered by professionals as a very useful tool for all phases of a construction project. BIM technology, with the particularly useful 3D illustrations which it provides, can be used to illustrate and monitor the progress of works effectively through the entire lifetime of the project. Unmanned Aerial Vehicles (UAVs) have undergone significant advances in equipment capabilities and now have the capacity to acquire high resolution imagery from different angles in a cost effective and efficient manner. By using photogrammetry, characteristics such as distances, areas, volumes, elevations, object sizes, and object shape can be determined within overlapping areas. This paper explores the combined use of BIM and UAV technologies in order to achieve efficient and accurate as-built data collection and 3D illustrations of the works progress during an infrastructure construction project.

'Big Bang' tomography as a new route to atomic-resolution electron tomography.

PubMed

Van Dyck, Dirk; Jinschek, Joerg R; Chen, Fu-Rong

2012-06-13

Until now it has not been possible to image at atomic resolution using classical electron tomographic methods, except when the target is a perfectly crystalline nano-object imaged along a few zone axes. The main reasons are that mechanical tilting in an electron microscope with sub-ångström precision over a very large angular range is difficult, that many real-life objects such as dielectric layers in microelectronic devices impose geometrical constraints and that many radiation-sensitive objects such as proteins limit the total electron dose. Hence, there is a need for a new tomographic scheme that is able to deduce three-dimensional information from only one or a few projections. Here we present an electron tomographic method that can be used to determine, from only one viewing direction and with sub-ångström precision, both the position of individual atoms in the plane of observation and their vertical position. The concept is based on the fact that an experimentally reconstructed exit wave consists of the superposition of the spherical waves that have been scattered by the individual atoms of the object. Furthermore, the phase of a Fourier component of a spherical wave increases with the distance of propagation at a known 'phase speed'. If we assume that an atom is a point-like object, the relationship between the phase and the phase speed of each Fourier component is linear, and the distance between the atom and the plane of observation can therefore be determined by linear fitting. This picture has similarities with Big Bang cosmology, in which the Universe expands from a point-like origin such that the distance of any galaxy from the origin is linearly proportional to the speed at which it moves away from the origin (Hubble expansion). The proof of concept of the method has been demonstrated experimentally for graphene with a two-layer structure and it will work optimally for similar layered materials, such as boron nitride and molybdenum disulphide.

A Passive Learning Sensor Architecture for Multimodal Image Labeling: An Application for Social Robots.

PubMed

Gutiérrez, Marco A; Manso, Luis J; Pandya, Harit; Núñez, Pedro

2017-02-11

Object detection and classification have countless applications in human-robot interacting systems. It is a necessary skill for autonomous robots that perform tasks in household scenarios. Despite the great advances in deep learning and computer vision, social robots performing non-trivial tasks usually spend most of their time finding and modeling objects. Working in real scenarios means dealing with constant environment changes and relatively low-quality sensor data due to the distance at which objects are often found. Ambient intelligence systems equipped with different sensors can also benefit from the ability to find objects, enabling them to inform humans about their location. For these applications to succeed, systems need to detect the objects that may potentially contain other objects, working with relatively low-resolution sensor data. A passive learning architecture for sensors has been designed in order to take advantage of multimodal information, obtained using an RGB-D camera and trained semantic language models. The main contribution of the architecture lies in the improvement of the performance of the sensor under conditions of low resolution and high light variations using a combination of image labeling and word semantics. The tests performed on each of the stages of the architecture compare this solution with current research labeling techniques for the application of an autonomous social robot working in an apartment. The results obtained demonstrate that the proposed sensor architecture outperforms state-of-the-art approaches.

Quality assessment of the TLS data in conservation of monuments

NASA Astrophysics Data System (ADS)

Markiewicz, Jakub S.; Zawieska, Dorota

2015-06-01

Laser scanning has been recently confirming its high potential in the field of acquiring 3D data for architectural and engineering objects. The objective of this paper is to analyse the quality of the TLS data acquired for different surfaces of monumental objects, with consideration of distances and the scanning angles. Tests concerning the quality of the survey data and shapes of architectural objects, characterised by diversified curvature, structure and the uniformity of the surface, were performed. The obtained results proved that utilisation of terrestrial laser scanning techniques does not allow to achieve expected accuracy for some historical surfaces and it should be substituted by alternative, photogrammetric techniques. Therefore, the typology of constructions of historical objects is important not only for selection of the optimum technique of surveys, but also for its appropriate utilisation. The test objects were architectural details of the Main Hall of the Warsaw University of Technology. Scans were acquired using the 5006h scanner. Diversified geometry of scans was tested, and the relations between the distance and obtained accuracy were specified. In the case of numerous conservational works the precise surface reconstruction is often important, in order to specify damages. Therefore, the repeatability of obtained TLS results for selected surfaces was also tested. Different surfaces were analysed, which are composed of different materials having glittery elements and inhomogeneous structure. The obtained results and performed analyses revealed the high imperfections of the TLS technique applied for measuring surfaces of historical objects. The presented accuracy of measurements of projection of historical surfaces, obtained using the TLS technique may be applied by art conservators, museum professionals, archaeologists and other specialists, to perform wide analyses of historical heritage objects.

Multiple wavelength interferometry for distance measurements of moving objects with nanometer uncertainty

NASA Astrophysics Data System (ADS)

Kuschmierz, R.; Czarske, J.; Fischer, A.

2014-08-01

Optical measurement techniques offer great opportunities in diverse applications, such as lathe monitoring and microfluidics. Doppler-based interferometric techniques enable simultaneous measurement of the lateral velocity and axial distance of a moving object. However, there is a complementarity between the unambiguous axial measurement range and the uncertainty of the distance. Therefore, we present an extended sensor setup, which provides an unambiguous axial measurement range of 1 mm while achieving uncertainties below 100 nm. Measurements at a calibration system are performed. When using a pinhole for emulating a single scattering particle, the tumbling motion of the rotating object is resolved with a distance uncertainty of 50 nm. For measurements at the rough surface, the distance uncertainty amounts to 280 nm due to a lower signal-to-noise ratio. Both experimental results are close to the respective Cramér-Rao bound, which is derived analytically for both surface and single particle measurements.

Predicting gravitational lensing by stellar remnants

NASA Astrophysics Data System (ADS)

Harding, Alexander J.; Stefano, R. Di; Lépine, S.; Urama, J.; Pham, D.; Baker, C.

2018-03-01

Gravitational lensing provides a means to measure mass that does not rely on detecting and analysing light from the lens itself. Compact objects are ideal gravitational lenses, because they have relatively large masses and are dim. In this paper, we describe the prospects for predicting lensing events generated by the local population of compact objects, consisting of 250 neutron stars, five black holes, and ≈35 000 white dwarfs. By focusing on a population of nearby compact objects with measured proper motions and known distances from us, we can measure their masses by studying the characteristics of any lensing event they generate. Here, we concentrate on shifts in the position of a background source due to lensing by a foreground compact object. With Hubble Space Telescope, JWST, and Gaia, measurable centroid shifts caused by lensing are relatively frequent occurrences. We find that 30-50 detectable events per decade are expected for white dwarfs. Because relatively few neutron stars and black holes have measured distances and proper motions, it is more difficult to compute realistic rates for them. However, we show that at least one isolated neutron star has likely produced detectable events during the past several decades. This work is particularly relevant to the upcoming data releases by the Gaia mission and also to data that will be collected by JWST. Monitoring predicted microlensing events will not only help to determine the masses of compact objects, but will also potentially discover dim companions to these stellar remnants, including orbiting exoplanets.

Eat Me If You Can: Cognitive Mechanisms Underlying the Distance Effect

PubMed Central

Junghans, Astrid F.; Evers, Catharine; De Ridder, Denise T. D.

2013-01-01

Proximal objects provide affordances that activate the motor information involved in interacting with the objects. This effect has previously been shown for artifacts but not for natural objects, such as food. This study examined whether the sight of proximal food, compared to distant food activates eating-related information. In two experiments reaction times to verbal labels following the sight of proximal and distant objects (food and toys) were measured. Verbal labels included function words that were compatible with one object category (eating and playing) and observation words compatible with both object categories. The sight of food was expected to activate eating-related information when presented at proximity but not at distance, as reflected by faster reaction times to proximal than distant compatible eating words and no difference between reaction times to proximal and distant food for observation words (Experiment 1). Experiment 2 additionally compared the reaction times to wrapped and unwrapped food. The distance effect was expected to occur only for unwrapped food because only unwrapped food is readily edible. As expected, Experiment 1 and 2 revealed faster responses to compatible eating words at proximity than at distance. In Experiment 2 this distance effect occurred only for readily edible, unwrapped food but not for wrapped food. For observation words no difference in response times between the distances was found. These findings suggest that the sight of proximal food activates eating-related information, which could explain people’s differential behavioral responses to reachable versus distant food. The activation of eating-related information upon sight of accessible food could provide a cognition-based explanation for mindless eating. PMID:24367684

Effect of Shot Peening in Different Shot Distance and Shot Angle on Surface Morphology, Surface Roughness and Surface Hardness of 316L Biomaterial

NASA Astrophysics Data System (ADS)

Umbu Kondi Maliwemu, Erich; Malau, Viktor; Iswanto, Priyo Tri

2018-01-01

Shot peening is a mechanical surface treatment with a beneficial effect to generate compressive residual stress caused by plastic deformation on the surface of material. This plastic deformation can improve the surface characteristics of metallic materials, such as modification of surface morphology, surface roughness, and surface hardness. The objective of this study is to investigate the effect of shot peening in different shot distance and shot angle on surface morphology, surface roughness, and surface hardness of 316L biomaterial. Shot distance was varied at 6, 8, 10, and 12 cm and shot angle at 30, 60, and 90°, working pressure at 7 kg/cm2, shot duration for 20 minutes, and using steel balls S-170 with diameter of 0.6 mm. The results present that the shot distance and shot angle of shot peening give the significant effect to improve the surface morphology, surface roughness, and surface hardness of 316 L biomaterial. Shot peening can increase the surface roughness by the increasing of shot distance and by the decreasing of shot angle. The nearest shot distance (6 cm) and the largest shot angle (90°) give the best results on the grain refinement with the surface roughness of 1.04 μm and surface hardness of 534 kg/mm2.

Go Long! Identifying Distant Brown Dwarfs in HST/WFC3 Parallel Field

NASA Astrophysics Data System (ADS)

Aganze, Christian; Burgasser, Adam J.; Malkan, Matthew Arnold; Masters, Daniel C.; Mercado, Gretel; Suarez, Adrian; Tamiya, Tomoki

2016-01-01

The spatial distribution of brown dwarfs beyond the local Solar Neighborhood is crucial for understanding their Galactic formation, dynamical and evolutionary history. Wide-field red optical and infrared surveys (e.g., 2MASS, SDSS, WISE) have enabled measures of the local density of brown dwarfs, but probe a relatively shallow (˜100 parsecs) volume; few constraints exist for the scale height or radial distributions of these low mass and low luminosity objects. We have searched ~1400 square arcminutes of WFC3 Infrared Spectroscopic Parallel Survey (WISPS) data to identify distant brown dwarfs (d > 300 pc) with near-infrared grism spectra from the the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). Using spectral indices to identify candidates, measure spectral types and estimate distances, and comparing the WFC3 spectra to spectral templates in the SpeX Prism Library, we report our first results from this work, the discovery of ~50 late-M, L and T dwarfs with distances of 30 - 1000+ pc. We compare the distance and spectral type distribution to population simulations, and discuss current selection biases.The material presented here is based on work supported by the National Aeronautics and Space Administration under Grant No. NNX15AI75G

Mach's Principle to Hubble's Law and Light Relativity

NASA Astrophysics Data System (ADS)

Zhang, Tianxi

2018-01-01

Discovery of the redshift-distance relation to be linear (i.e. Hubble's law) for galaxies in the end of 1920s instigated us to widely accept expansion of the universe, originated from a big bang around 14 billion years ago. Finding of the redshift-distance relation to be weaker than linear for distant type Ia supernovae nearly two decades ago further precipitated us to largely agree with recent acceleration of the universe, driven by the mysterious dark energy. The time dilation measured for supernovae has been claimed as a direct evidence for the expansion of the universe, but scientists could not explain why quasars and gamma-ray bursts had not similar time dilations. Recently, an anomaly was found in the standard template for the width of supernova light curves to be proportional to the wavelength, which exactly removed the time dilation of supernovae and hence was strongly inconsistent with the conventional redshift mechanism. In this study, we have derived a new redshift-distance relation from Mach's principle with light relativity that describes the effect of light on spacetime as well as the influence of disturbed spacetime on the light inertia or frequency. A moving object or photon, because of its continuously keeping on displacement, disturbs the rest of the entire universe or distorts/curves the spacetime. The distorted or curved spacetime then generates an effective gravitational force to act back on the moving object or photon, so that reduces the object inertia or photon frequency. Considering the disturbance of spacetime by a photon is extremely weak, we have modelled the effective gravitational force to be Newtonian and derived the new redshift-distance relation that can not only perfectly explain the redshift-distance measurement of distant type Ia supernovae but also inherently obtain Hubble's law as an approximate at small redshift. Therefore, the result obtained from this study does neither support the acceleration of the universe nor the expansion of the universe but prefers to Einstein's simplest cosmology of the static universe or Zhang's static or dynamic cosmology of the black hole universe. This work was partially supported by NSF/REU (Grant #: PHY-1559870) at Alabama A & M University

Gaze behavior and the perception of egocentric distance

PubMed Central

Gajewski, Daniel A.; Wallin, Courtney P.; Philbeck, John W.

2014-01-01

The ground plane is thought to be an important reference for localizing objects, particularly when angular declination is informative, as it is for objects seen resting at floor level. A potential role for eye movements has been implicated by the idea that information about the nearby ground is required to localize objects more distant, and by the fact that the time course for the extraction of distance extends beyond the duration of a typical eye fixation. To test this potential role, eye movements were monitored when participants previewed targets. Distance estimates were provided by walking without vision to the remembered target location (blind walking) or by verbal report. We found that a strategy of holding the gaze steady on the object was as frequent as one where the region between the observer and object was fixated. There was no performance advantage associated with making eye movements in an observational study (Experiment 1) or when an eye-movement strategy was manipulated experimentally (Experiment 2). Observers were extracting useful information covertly, however. In Experiments 3 through 5, obscuring the nearby ground plane had a modest impact on performance; obscuring the walls and ceiling was more detrimental. The results suggest that these alternate surfaces provide useful information when judging the distance to objects within indoor environments. Critically, they constrain the role for the nearby ground plane in theories of egocentric distance perception. PMID:24453346

Building capacity without disrupting health services: public health education for Africa through distance learning.

PubMed

Alexander, Lucy; Igumbor, Ehi Uche; Sanders, David

2009-04-01

The human resources crisis in Africa is especially acute in the public health field. Through distance education, the School of Public Health of the University of the Western Cape, South Africa, has provided access to master's level public health education for health professionals from more than 20 African countries while they remain in post. Since 2000, interest has increased overwhelmingly to a point where four times more applications are received than can be accommodated. This home-grown programme remains sensitive to the needs of the target learners while engaging them in high-quality learning applied in their own work contexts. This brief paper describes the innovative aspects of the programme, offering some evaluative indications of its impact, and reviews how the delivery of text-led distance learning has facilitated the realization of the objectives of public health training. Strategies are proposed for scaling up such a programme to meet the growing need in this essential area of health human resource capacity development in Africa.

Building capacity without disrupting health services: public health education for Africa through distance learning

PubMed Central

Alexander, Lucy; Igumbor, Ehi Uche; Sanders, David

2009-01-01

The human resources crisis in Africa is especially acute in the public health field. Through distance education, the School of Public Health of the University of the Western Cape, South Africa, has provided access to master's level public health education for health professionals from more than 20 African countries while they remain in post. Since 2000, interest has increased overwhelmingly to a point where four times more applications are received than can be accommodated. This home-grown programme remains sensitive to the needs of the target learners while engaging them in high-quality learning applied in their own work contexts. This brief paper describes the innovative aspects of the programme, offering some evaluative indications of its impact, and reviews how the delivery of text-led distance learning has facilitated the realization of the objectives of public health training. Strategies are proposed for scaling up such a programme to meet the growing need in this essential area of health human resource capacity development in Africa. PMID:19338669

Cutting the Distance in Distance Education: Reflections on the Use of E-Technologies in a New Zealand Social Work Program

ERIC Educational Resources Information Center

Stanley-Clarke, Nicky; English, Awhina; Yeung, Polly

2018-01-01

The development of new e-technologies and an increased focus on developing distance social work education programs has created the impetus for social work educators to consider the tools they can employ in delivering distance courses. This article reflects on an action learning research project involving the development of an online toolbox of…

Moving Object Control System

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)

2001-01-01

A method is provided for controlling two objects relatively moveable with respect to each other. A plurality of receivers are provided for detecting a distinctive microwave signal from each of the objects and measuring the phase thereof with respect to a reference signal. The measured phase signal is used to determine a distance between each of the objects and each of the plurality of receivers. Control signals produced in response to the relative distances are used to control the position of the two objects.

Concealed object segmentation and three-dimensional localization with passive millimeter-wave imaging

NASA Astrophysics Data System (ADS)

Yeom, Seokwon

2013-05-01

Millimeter waves imaging draws increasing attention in security applications for weapon detection under clothing. In this paper, concealed object segmentation and three-dimensional localization schemes are reviewed. A concealed object is segmented by the k-means algorithm. A feature-based stereo-matching method estimates the longitudinal distance of the concealed object. The distance is estimated by the discrepancy between the corresponding centers of the segmented objects. Experimental results are provided with the analysis of the depth resolution.

Intelligent lead: a novel HRI sensor for guide robots.

PubMed

Cho, Keum-Bae; Lee, Beom-Hee

2012-01-01

This paper addresses the introduction of a new Human Robot Interaction (HRI) sensor for guide robots. Guide robots for geriatric patients or the visually impaired should follow user's control command, keeping a certain desired distance allowing the user to work freely. Therefore, it is necessary to acquire control commands and a user's position on a real-time basis. We suggest a new sensor fusion system to achieve this objective and we will call this sensor the "intelligent lead". The objective of the intelligent lead is to acquire a stable distance from the user to the robot, speed-control volume and turn-control volume, even when the robot platform with the intelligent lead is shaken on uneven ground. In this paper we explain a precise Extended Kalman Filter (EKF) procedure for this. The intelligent lead physically consists of a Kinect sensor, the serial linkage attached with eight rotary encoders, and an IMU (Inertial Measurement Unit) and their measurements are fused by the EKF. A mobile robot was designed to test the performance of the proposed sensor system. After installing the intelligent lead in the mobile robot, several tests are conducted to verify that the mobile robot with the intelligent lead is capable of achieving its goal points while maintaining the appropriate distance between the robot and the user. The results show that we can use the intelligent lead proposed in this paper as a new HRI sensor joined a joystick and a distance measure in the mobile environments such as the robot and the user are moving at the same time.

Fuzzy logic controller to improve powerline communication

NASA Astrophysics Data System (ADS)

Tirrito, Salvatore

2015-12-01

The Power Line Communications (PLC) technology allows the use of the power grid in order to ensure the exchange of data information among devices. This work proposes an approach, based on Fuzzy Logic, that dynamically manages the amplitude of the signal, with which each node transmits, by processing the master-slave link quality measured and the master-slave distance. The main objective of this is to reduce both the impact of communication interferences induced and power consumption.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gofron, K. J., E-mail: kgofron@bnl.gov; Cai, Y. Q.; Coburn, D. S.

A novel on-axis X-ray microscope with 3 µm resolution, 3x magnification, and a working distance of 600 mm for in-situ sample alignment and X-ray beam visualization for the Inelastic X-ray Scattering (IXS) beamline at NSLS-II is presented. The microscope uses reflective optics, which minimizes dispersion, and allows imaging from Ultraviolet (UV) to Infrared (IR) with specifically chosen objective components (coatings, etc.). Additionally, a portable high resolution X-ray microscope for KB mirror alignment and X-ray beam characterization was developed.

Relation of Young Infants' Reaching Behavior to Stimulus Distance and Solidity

ERIC Educational Resources Information Center

Field, Jeffery

1976-01-01

The reaching behavior of 12 infants in the presence of solid objects and pictures of objects placed within and beyond possible contact distance was videotaped in three sessions at 15, 19, and 24 weeks of age. (Author/MS)

Distributed proximity sensor system having embedded light emitters and detectors

NASA Technical Reports Server (NTRS)

Lee, Sukhan (Inventor)

1990-01-01

A distributed proximity sensor system is provided with multiple photosensitive devices and light emitters embedded on the surface of a robot hand or other moving member in a geometric pattern. By distributing sensors and emitters capable of detecting distances and angles to points on the surface of an object from known points in the geometric pattern, information is obtained for achieving noncontacting shape and distance perception, i.e., for automatic determination of the object's shape, direction and distance, as well as the orientation of the object relative to the robot hand or other moving member.

Current Challenges in Social Work Distance Education: Responses from the Elluminati

ERIC Educational Resources Information Center

Pelech, William; Wulff, Dan; Perrault, Ellen; Ayala, Jessica; Baynton, Myra; Williams, Margaret; Crowder, Rachael; Shankar, Janki

2013-01-01

One of the first tasks of the Social Work Distance Education Network at the Faculty of Social Work at the University of Calgary was to review the literature and address three research questions to inform policy making and planning relating to distance social work education programming. This paper is intended to disseminate responses to these…

Vocational Education at a Distance: International Perspectives. New Developments in Vocational Education.

ERIC Educational Resources Information Center

Rumble, Greville, Ed.; Oliveira, Joao, Ed.

This book contains the following papers on distance vocational education programs: "Vocational Education at a Distance" (Oliveira, Rumble); "An Introduction to Case Studies" (Oliveira, Rumble); "'Working on Work': Orientation on Work and the Labour Market in the Netherlands" (Bender, Bronkhorst); "Expanding…

Tachistoscopic illumination and masking of real scenes

PubMed Central

Chichka, David; Philbeck, John W.; Gajewski, Daniel A.

2014-01-01

Tachistoscopic presentation of scenes has been valuable for studying the emerging properties of visual scene representations. The spatial aspects of this work have generally been focused on the conceptual locations (e.g., next to the refrigerator) and the directional locations of objects in 2D arrays and/or images. Less is known about how the perceived egocentric distance of objects develops. Here we describe a novel system for presenting brief glimpses of a real-world environment, followed by a mask. The system includes projectors with mechanical shutters for projecting the fixation and masking images, a set of LED floodlights for illuminating the environment, and computer-controlled electronics to set the timing and initiate the process. Because a real environment is used, most visual distance and depth cues may be manipulated using traditional methods. The system is inexpensive, robust, and its components are readily available in the marketplace. This paper describes the system and the timing characteristics of each component. Verification of the ability to control exposure to time scales as low as a few milliseconds is demonstrated. PMID:24519496

Do Object-Category Selective Regions in the Ventral Visual Stream Represent Perceived Distance Information?

ERIC Educational Resources Information Center

Amit, Elinor; Mehoudar, Eyal; Trope, Yaacov; Yovel, Galit

2012-01-01

It is well established that scenes and objects elicit a highly selective response in specific brain regions in the ventral visual cortex. An inherent difference between these categories that has not been explored yet is their perceived distance from the observer (i.e. scenes are distal whereas objects are proximal). The current study aimed to test…

Scanning Electrochemical Microscopy in Neuroscience

NASA Astrophysics Data System (ADS)

Schulte, Albert; Nebel, Michaela; Schuhmann, Wolfgang

2010-07-01

This article reviews recent work involving the application of scanning electrochemical microscopy (SECM) to the study of individual cultured living cells, with an emphasis on topographical and functional imaging of neuronal and secretory cells of the nervous and endocrine system. The basic principles of biological SECM and associated negative amperometric-feedback and generator/collector-mode SECM imaging are discussed, and successful use of the methodology for screening soft and fragile membranous objects is outlined. The drawbacks of the constant-height mode of probe movement and the benefits of the constant-distance mode of SECM operation are described. Finally, representative examples of constant-height and constant-distance mode SECM on a variety of live cells are highlighted to demonstrate the current status of single-cell SECM in general and of SECM in neuroscience in particular.

Distance Determination by Gated Viewing Systems Taking into Account the Illuminating Pulse Shape

NASA Astrophysics Data System (ADS)

Gorobets, V. A.; Kuntsevich, B. F.; Shabrov, D. V.

2017-11-01

For gated viewing systems with triangular and trapezoidal illuminating pulses, we have obtained the range-intensity profiles (RIPs) of the signal as the time delay was varied between the leading edges of the gate pulse and the illuminating pulse. We have established that if the duration of the illuminating pulse Δtlas is less than or equal to the duration of the gate pulse ΔtIC, then the expressions for the characteristic distances are the same as for rectangular pulses and they can be used to determine the distance to objects. When Δtlas > ΔtIC, in the case of triangular illuminating pulses the RIP is bell-shaped. For trapezoidal pulses, the RIP is bell-shaped with or without a plateau section. We propose an empirical method for determining the characteristic distances to the RIP maximum and the boundary points for the plateau section, which we then use to calculate the distance to the object. Using calibration constants, we propose a method for determining the distance to an object and we have experimentally confirmed the feasibility of this method.

Determination of Non-gravitational Effects in the Motion of Near-Sun Objects 321P, 322P, 323P, and 342P

NASA Astrophysics Data System (ADS)

Emel'yanenko, V. V.; Naroenkov, S. A.

2018-01-01

At the beginning of this century, the SOHO space observatory discovered near-Sun comets with perihelion distances q ≈ 0.05 AU, which remained observable over several close encounters with the Sun. This became one of the surprises in studying the small bodies of the Solar System. Currently, there are objects that have already been observed in four (342P) and five (321P, 322P, and 323P) apparitions. In the present work, the estimates of nongravitational effects are obtained for these objects based on the pair-wise linkage of the apparitions. The calculations show that the observations of these objects are poorly represented if solely the gravitational forces are considered. The magnitude of nongravitational effects in the semimajor axis noticeably changes with time. The motion of all comets is significantly affected by the components of nongravitational forces that are perpendicular to the orbital plane.

Vision Algorithms to Determine Shape and Distance for Manipulation of Unmodeled Objects

NASA Technical Reports Server (NTRS)

Montes, Leticia; Bowers, David; Lumia, Ron

1998-01-01

This paper discusses the development of a robotic system for general use in an unstructured environment. This is illustrated through pick and place of randomly positioned, un-modeled objects. There are many applications for this project, including rock collection for the Mars Surveyor Program. This system is demonstrated with a Puma560 robot, Barrett hand, Cognex vision system, and Cimetrix simulation and control, all running on a PC. The demonstration consists of two processes: vision system and robotics. The vision system determines the size and location of the unknown objects. The robotics part consists of moving the robot to the object, configuring the hand based on the information from the vision system, then performing the pick/place operation. This work enhances and is a part of the Low Cost Virtual Collaborative Environment which provides remote simulation and control of equipment.

A novel 3D shape descriptor for automatic retrieval of anatomical structures from medical images

NASA Astrophysics Data System (ADS)

Nunes, Fátima L. S.; Bergamasco, Leila C. C.; Delmondes, Pedro H.; Valverde, Miguel A. G.; Jackowski, Marcel P.

2017-03-01

Content-based image retrieval (CBIR) aims at retrieving from a database objects that are similar to an object provided by a query, by taking into consideration a set of extracted features. While CBIR has been widely applied in the two-dimensional image domain, the retrieval of3D objects from medical image datasets using CBIR remains to be explored. In this context, the development of descriptors that can capture information specific to organs or structures is desirable. In this work, we focus on the retrieval of two anatomical structures commonly imaged by Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) techniques, the left ventricle of the heart and blood vessels. Towards this aim, we developed the Area-Distance Local Descriptor (ADLD), a novel 3D local shape descriptor that employs mesh geometry information, namely facet area and distance from centroid to surface, to identify shape changes. Because ADLD only considers surface meshes extracted from volumetric medical images, it substantially diminishes the amount of data to be analyzed. A 90% precision rate was obtained when retrieving both convex (left ventricle) and non-convex structures (blood vessels), allowing for detection of abnormalities associated with changes in shape. Thus, ADLD has the potential to aid in the diagnosis of a wide range of vascular and cardiac diseases.

Measuring the Psychological Distance between an Organization and Its Members—The Construction and Validation of a New Scale

PubMed Central

Chen, Hong; Li, Shanshan

2018-01-01

There exists a lack of specific research methods to estimate the relationship between an organization and its employees, which has long challenged research in the field of organizational management. Therefore, this article introduces psychological distance concept into the research of organizational behavior, which can define the concept of psychological distance between employees and an organization and describe a level of perceived correspondence or interaction between subjects and objects. We developed an employee-organization psychological distance (EOPD) scale through both qualitative and quantitative analysis methods. As indicated by the research results based on grounded theory (10 employee in-depth interview records and 277 opening questionnaires) and formal investigation (544 questionnaires), this scale consists of six dimensions: experiential distance, behavioral distance, emotional distance, cognitive distance, spatial-temporal distance, and objective social distance based on 44 items. Finally, we determined that the EOPD scale exhibited acceptable reliability and validity using confirmatory factor analysis. This research may establish a foundation for future research on the measurement of psychological relationships between employees and organizations. PMID:29375427

An Approach for the Distance Delivery of AFIT/LS Resident Degree Curricula

DTIC Science & Technology

1991-12-01

minimal (least complex) distance education technologies appropriate for each learning topic or task. This may be the most time-consuming step in the...34 represents the least complex distance education technology that could be used to deliver the educational material for a particular learning objective. Careful...minimal technology needed to accomplish the learning objective. Look at question Q2.1 (Figure 5.15). Since the lecture offers an essential educational

Pharmacists' perceptions of a live continuing education program comparing distance learning versus local learning.

PubMed

Buxton, Eric C; De Muth, James E

2013-01-01

Constraints in geography and time require cost efficiencies in professional development for pharmacists. Distance learning, with its growing availability and lower intrinsic costs, will likely become more prevalent. The objective of this nonexperimental, postintervention study was to examine the perceptions of pharmacists attending a continuing education program. One group participated in the live presentation, whereas the second group joined via a simultaneous webcast. After the presentation, both groups were surveyed with identical questions concerning their perceptions of their learning environment, course content, and utility to their work. Comparisons across group responses to the summated scales were conducted through the use of Kruskal-Wallis tests. Analysis of the data showed that both the distance and local groups were demographically similar and that both groups were satisfied with the presentation method, audio and visual quality, and both felt that they would be able to apply what they learned in their practice. However, the local group was significantly more satisfied with the learning experience. Distance learning does provide a viable and more flexible method for pharmacy professional development, but does not yet replace the traditional learning environment in all facets of learner preference. Copyright © 2013 Elsevier Inc. All rights reserved.

Using Blur to Affect Perceived Distance and Size

PubMed Central

HELD, ROBERT T.; COOPER, EMILY A.; O’BRIEN, JAMES F.; BANKS, MARTIN S.

2011-01-01

We present a probabilistic model of how viewers may use defocus blur in conjunction with other pictorial cues to estimate the absolute distances to objects in a scene. Our model explains how the pattern of blur in an image together with relative depth cues indicates the apparent scale of the image’s contents. From the model, we develop a semiautomated algorithm that applies blur to a sharply rendered image and thereby changes the apparent distance and scale of the scene’s contents. To examine the correspondence between the model/algorithm and actual viewer experience, we conducted an experiment with human viewers and compared their estimates of absolute distance to the model’s predictions. We did this for images with geometrically correct blur due to defocus and for images with commonly used approximations to the correct blur. The agreement between the experimental data and model predictions was excellent. The model predicts that some approximations should work well and that others should not. Human viewers responded to the various types of blur in much the way the model predicts. The model and algorithm allow one to manipulate blur precisely and to achieve the desired perceived scale efficiently. PMID:21552429

Near or far: The effect of spatial distance and vocabulary knowledge on word learning.

PubMed

Axelsson, Emma L; Perry, Lynn K; Scott, Emilly J; Horst, Jessica S

2016-01-01

The current study investigated the role of spatial distance in word learning. Two-year-old children saw three novel objects named while the objects were either in close proximity to each other or spatially separated. Children were then tested on their retention for the name-object associations. Keeping the objects spatially separated from each other during naming was associated with increased retention for children with larger vocabularies. Children with a lower vocabulary size demonstrated better retention if they saw objects in close proximity to each other during naming. This demonstrates that keeping a clear view of objects during naming improves word learning for children who have already learned many words, but keeping objects within close proximal range is better for children at earlier stages of vocabulary acquisition. The effect of distance is therefore not equal across varying vocabulary sizes. The influences of visual crowding, cognitive load, and vocabulary size on word learning are discussed. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Distance Education Programs in Social Work: Current and Emerging Trends

ERIC Educational Resources Information Center

Vernon, Robert; Vakalahi, Halaevalu; Pierce, Dean; Pittman-Munke, Peggy; Adkins, Lynn Frantz

2009-01-01

This article reports on current and emerging trends in the use of distance education technologies in social work education. Areas studied include the extent of distance education programs, curricular areas covered, technologies used, pedagogical approaches, intentions for degree-program development, sources of pressure to adopt distance education…

An alternative approach to depth of field which avoids the blur circle and uses the pixel pitch

NASA Astrophysics Data System (ADS)

Schuster, Norbert

2015-09-01

Modern thermal imaging systems apply more and more uncooled detectors. High volume applications work with detectors which have a reduced pixel count (typical between 200x150 and 640x480). This shrinks the application of modern image treatment procedures like wave front coding. On the other hand side, uncooled detectors demand lenses with fast F-numbers near 1.0. Which are the limits on resolution if the target to analyze changes its distance to the camera system? The aim to implement lens arrangements without any focusing mechanism demands a deeper quantification of the Depth of Field problem. The proposed Depth of Field approach avoids the classic "accepted image blur circle". It bases on a camera specific depth of focus which is transformed in the object space by paraxial relations. The traditional RAYLEIGH's -criterion bases on the unaberrated Point Spread Function and delivers a first order relation for the depth of focus. Hence, neither the actual lens resolution neither the detector impact is considered. The camera specific depth of focus respects a lot of camera properties: Lens aberrations at actual F-number, detector size and pixel pitch. The through focus MTF is the base of the camera specific depth of focus. It has a nearly symmetric course around the maximum of sharp imaging. The through focus MTF is considered at detector's Nyquist frequency. The camera specific depth of focus is this the axial distance in front and behind of sharp image plane where the through focus MTF is <0.25. This camera specific depth of focus is transferred in the object space by paraxial relations. It follows a general applicable Depth of Field diagram which could be applied to lenses realizing a lateral magnification range -0.05…0. Easy to handle formulas are provided between hyperfocal distance and the borders of the Depth of Field in dependence on sharp distances. These relations are in line with the classical Depth of Field-theory. Thermal pictures, taken by different IR-camera cores, illustrate the new approach. The quite often requested graph "MTF versus distance" choses the half Nyquist frequency as reference. The paraxial transfer of the through focus MTF in object space distorts the MTF-curve: hard drop at closer distances than sharp distance, smooth drop at further distances. The formula of a general Diffraction-Limited-Through-Focus-MTF (DLTF) is deducted. Arbitrary detector-lens combinations could be discussed. Free variables in this analysis are waveband, aperture based F-number (lens) and pixel pitch (detector). The DLTF- discussion provides physical limits and technical requirements. The detector development with pixel pitches smaller than captured wavelength in the LWIR-region generates a special challenge for optical design.

Ghost imaging via optical parametric amplification

NASA Astrophysics Data System (ADS)

Li, Hong-Guo; Zhang, De-Jian; Xu, De-Qin; Zhao, Qiu-Li; Wang, Sen; Wang, Hai-Bo; Xiong, Jun; Wang, Kaige

2015-10-01

We investigate theoretically and experimentally thermal light ghost imaging where the light transmitted through the object as the seed light is amplified by an optical parametric amplifier (OPA). In conventional lens imaging systems with OPA, the spectral bandwidth of OPA dominates the image resolution. Theoretically, we prove that in ghost imaging via optical parametric amplification (GIOPA) the bandwidth of OPA will not affect the image resolution. The experimental results show that for weak seed light the image quality in GIOPA is better than that of conventional ghost imaging. Our work may be valuable in remote sensing with ghost imaging technique, where the light passed through the object is weak after a long-distance propagation.

Fluctuations in Conjunction Miss Distance Projections as Time Approaches Time of Closest Approach

NASA Technical Reports Server (NTRS)

Christian, John A., III

2005-01-01

A responsibility of the Trajectory Operations Officer is to ensure that the International Space Station (ISS) avoids colliding with debris. United States Space Command (USSPACECOM) tracks and catalogs a portion of the debris in Earth orbit, but only objects with a perigee less than 600 km and a radar cross section (RCS) greater than 10 cm-objects that, in fact, represent only a small fraction of the objects in Earth orbit. To accommodate for this, the ISS uses shielding to protect against collisions with smaller objects. This study provides a better understanding of how quickly, and to what degree, USSPACECOM projections tend to converge to the final, true miss distance. The information included is formulated to better predict the behavior of miss distance data during real-time operations. It was determined that the driving components, in order of impact on miss distance fluctuations, are energy dissipation rate (EDR), RCS, and inclination. Data used in this analysis, calculations made, and conclusions drawn are stored in Microsoft Excel log sheets. A separate log sheet, created for each conjunction, contains information such as predicted miss distances, apogee and perigee of debris orbit, EDR, RCS, inclination, tracks and observations, statistical data, and other evaluation/orbital parameters.

C-arm technique using distance driven method for nephrolithiasis and kidney stones detection

NASA Astrophysics Data System (ADS)

Malalla, Nuhad; Sun, Pengfei; Chen, Ying; Lipkin, Michael E.; Preminger, Glenn M.; Qin, Jun

2016-04-01

Distance driven represents a state of art method that used for reconstruction for x-ray techniques. C-arm tomography is an x-ray imaging technique that provides three dimensional information of the object by moving the C-shaped gantry around the patient. With limited view angle, C-arm system was investigated to generate volumetric data of the object with low radiation dosage and examination time. This paper is a new simulation study with two reconstruction methods based on distance driven including: simultaneous algebraic reconstruction technique (SART) and Maximum Likelihood expectation maximization (MLEM). Distance driven is an efficient method that has low computation cost and free artifacts compared with other methods such as ray driven and pixel driven methods. Projection images of spherical objects were simulated with a virtual C-arm system with a total view angle of 40 degrees. Results show the ability of limited angle C-arm technique to generate three dimensional images with distance driven reconstruction.

Hierarchical Modelling Of Mobile, Seeing Robots

NASA Astrophysics Data System (ADS)

Luh, Cheng-Jye; Zeigler, Bernard P.

1990-03-01

This paper describes the implementation of a hierarchical robot simulation which supports the design of robots with vision and mobility. A seeing robot applies a classification expert system for visual identification of laboratory objects. The visual data acquisition algorithm used by the robot vision system has been developed to exploit multiple viewing distances and perspectives. Several different simulations have been run testing the visual logic in a laboratory environment. Much work remains to integrate the vision system with the rest of the robot system.

Hierarchical modelling of mobile, seeing robots

NASA Technical Reports Server (NTRS)

Luh, Cheng-Jye; Zeigler, Bernard P.

1990-01-01

This paper describes the implementation of a hierarchical robot simulation which supports the design of robots with vision and mobility. A seeing robot applies a classification expert system for visual identification of laboratory objects. The visual data acquisition algorithm used by the robot vision system has been developed to exploit multiple viewing distances and perspectives. Several different simulations have been run testing the visual logic in a laboratory environment. Much work remains to integrate the vision system with the rest of the robot system.

Social Work Education through Open and Distance Learning: An Indian Perspective

ERIC Educational Resources Information Center

Dash, Bishnu Mohan; Botcha, Rambabu

2018-01-01

The paper traces the historical perspectives of open and distance education in India. It also discusses the various modalities and standards followed by various universities in offering social work education through open and distance learning (ODL) mode. It also highlights the achievements and challenges of social work education through ODL mode…

Perspectives on Group Work in Distance Learning

ERIC Educational Resources Information Center

Hausstatter, Rune Sarromaa; Nordkvelle, Yngve Troye

2007-01-01

Current distance education benefits greatly from educational software that makes group work possible for students who are separated in time and space. However, some students prefer distance education because they can work on their own. This paper explores how students react to expectations on behalf of the course provider to do their assignments…

The relationship between diet and perceived and objective access to supermarkets among low-income housing residents

PubMed Central

Caspi, Caitlin E.; Kawachi, Ichiro; Subramanian, S.V.; Adamkiewicz, Gary; Sorensen, Glorian

2013-01-01

In the U.S., supermarkets serve as an important source of year-round produce (Chung & Myers, 1999), and yet access to supermarkets may be scarce in “food deserts,” or poor, urban areas that lack sources of healthy, affordable food (Cummins & Macintyre, 2002). This study examined objective distance to the nearest supermarket and participant-report of supermarket access in relation to fruit and vegetable intake. Street-network distance to the closest supermarket was calculated using GIS mapping. Perceived access was assessed by a survey question asking whether participants had a supermarket within walking distance of home. Cross-sectional survey data were collected from 828 low-income housing residents in three urban areas in greater-Boston. Generalized estimating equations were used to estimate the association between perceived and objective supermarket access and diet. Fruit and vegetable consumption was low (2.63 servings/day). Results suggest that most low-income housing residents in greater-Boston do not live in “food deserts,” as the average distance to a supermarket was 0.76 km (range 0.13–1.22 km). Distance to a supermarket was not associated with fruit and vegetable intake (p = 0.22). Perceived supermarket access was strongly associated with increased fruit and vegetable intake (0.5 servings/day) after controlling for socio-demographic covariates (p < 0.0001). Patterns of mismatch between perceived and objective measures revealed that mismatch between the two measures were high (31.45%). Those who did not report a supermarket within walking distance from home despite the objective presence of a supermarket within 1 km consumed significantly fewer fruits and vegetables (0.56 servings/day) than those with a supermarket who reported one, even after controlling for socio-demographic variables (p = 0.0008). Perceived measures of the food environment may be more strongly related to dietary behaviors than objective ones, and may incorporate components of food access not captured in objective measures. PMID:22727742

The relationship between diet and perceived and objective access to supermarkets among low-income housing residents.

PubMed

Caspi, Caitlin E; Kawachi, Ichiro; Subramanian, S V; Adamkiewicz, Gary; Sorensen, Glorian

2012-10-01

In the U.S., supermarkets serve as an important source of year-round produce (Chung & Myers, 1999), and yet access to supermarkets may be scarce in "food deserts," or poor, urban areas that lack sources of healthy, affordable food (Cummins & Macintyre, 2002). This study examined objective distance to the nearest supermarket and participant-report of supermarket access in relation to fruit and vegetable intake. Street-network distance to the closest supermarket was calculated using GIS mapping. Perceived access was assessed by a survey question asking whether participants had a supermarket within walking distance of home. Cross-sectional survey data were collected from 828 low-income housing residents in three urban areas in greater-Boston. Generalized estimating equations were used to estimate the association between perceived and objective supermarket access and diet. Fruit and vegetable consumption was low (2.63 servings/day). Results suggest that most low-income housing residents in greater-Boston do not live in "food deserts," as the average distance to a supermarket was 0.76 km (range 0.13-1.22 km). Distance to a supermarket was not associated with fruit and vegetable intake (p = 0.22). Perceived supermarket access was strongly associated with increased fruit and vegetable intake (0.5 servings/day) after controlling for socio-demographic covariates (p < 0.0001). Patterns of mismatch between perceived and objective measures revealed that mismatch between the two measures were high (31.45%). Those who did not report a supermarket within walking distance from home despite the objective presence of a supermarket within 1 km consumed significantly fewer fruits and vegetables (0.56 servings/day) than those with a supermarket who reported one, even after controlling for socio-demographic variables (p = 0.0008). Perceived measures of the food environment may be more strongly related to dietary behaviors than objective ones, and may incorporate components of food access not captured in objective measures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Deciphering the Distance between Distance Education and Working Professionals in Difficult Geographies

ERIC Educational Resources Information Center

Pandey, Jatin; Singh, Manjari

2015-01-01

This study investigates the factors that draw working professionals towards distance education programs, and the factors that sustain their distance education experience. The study is conducted in difficult terrains of Uttarakhand, a hilly state in India which helps us investigate the phenomenon in difficult geographies. Through interviews of ten…

Calibrating Reach Distance to Visual Targets

ERIC Educational Resources Information Center

Mon-Williams, Mark; Bingham, Geoffrey P.

2007-01-01

The authors investigated the calibration of reach distance by gradually distorting the haptic feedback obtained when participants grasped visible target objects. The authors found that the modified relationship between visually specified distance and reach distance could be captured by a straight-line mapping function. Thus, the relation could be…

[Family factors influence active commuting to school in Spanish children].

PubMed

Rodríguez-López, Carlos; Villa-González, Emilio; Pérez-López, Isaac J; Delgado-Fernández, Manuel; Ruiz, Jonatan R; Chillón, Palma

2013-01-01

Active commuting to school is associated to higher levels of physical activity among children. Family factors may influence on this behaviour. The objective was to analyze the association between parents' occupational activity and parents' mode of commuting to work with the mode of commuting of their children. A total of 721 families from 4 primary schools in the province of Granada participated in this study. Families reported a questionnaire about mode of commuting of their children, parents' occupational activity and mode of commuting to work, distance and travel time to school. Associations between family's occupational activity and mode of commuting to work with mode of commuting to school of their children were examined using binary logistic regression analysis adjusting for age and children's distance to school. Children whose parents did not work used to engage in higher levels of active commuting to school than those whose parents worked (p = 0,023; OR: 2,67; 95% CI: 1,14-6,23). Children whose parents used to commute actively to work used to engage in higher levels of active commuting to school than those whose parents both used passive modes of commuting to work (p = 0,014; OR: 6,30; 95% CI: 1,45-27,26). Family factors are related to mode of commuting to school in children: Unemployed families and employed families where parent are active commuters to work are more used to have children that commuted to school using active modes. Copyright © AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

Cooperative multisensor system for real-time face detection and tracking in uncontrolled conditions

NASA Astrophysics Data System (ADS)

Marchesotti, Luca; Piva, Stefano; Turolla, Andrea; Minetti, Deborah; Regazzoni, Carlo S.

2005-03-01

The presented work describes an innovative architecture for multi-sensor distributed video surveillance applications. The aim of the system is to track moving objects in outdoor environments with a cooperative strategy exploiting two video cameras. The system also exhibits the capacity of focusing its attention on the faces of detected pedestrians collecting snapshot frames of face images, by segmenting and tracking them over time at different resolution. The system is designed to employ two video cameras in a cooperative client/server structure: the first camera monitors the entire area of interest and detects the moving objects using change detection techniques. The detected objects are tracked over time and their position is indicated on a map representing the monitored area. The objects" coordinates are sent to the server sensor in order to point its zooming optics towards the moving object. The second camera tracks the objects at high resolution. As well as the client camera, this sensor is calibrated and the position of the object detected on the image plane reference system is translated in its coordinates referred to the same area map. In the map common reference system, data fusion techniques are applied to achieve a more precise and robust estimation of the objects" track and to perform face detection and tracking. The work novelties and strength reside in the cooperative multi-sensor approach, in the high resolution long distance tracking and in the automatic collection of biometric data such as a person face clip for recognition purposes.

Influence of Near Tasks on Posture in Myopic Chinese Schoolchildren

PubMed Central

Bao, Jinhua; Drobe, Björn; Wang, Yuwen; Chen, Ke; Seow, Eu Jin; Lu, Fan

2015-01-01

ABSTRACT Purpose To investigate near-vision posture in Chinese myopic schoolchildren and compare near-vision posture during different near-vision tasks (i.e., playing video games, reading, and writing). Methods The study investigated 120 myopic children (grades 1 through 6 and aged 6 to 13 years). An electromagnetic motion-tracking system was used for continuous measurements of the working distance and head declination of the subjects while they were playing video games or reading or writing at a desk. The reading and writing documents were adjusted by grade level (i.e., grades 1 to 2, 3 to 4, and 5 to 6). For analysis, the subjects were grouped in two refractive groups according to their median spherical equivalent refractive error (−1.50D). Results The myopic schoolchildren used close working distances for all tasks: 21.3 ± 5.2 cm (video games), 27.2 ± 6.4 cm (reading), and 24.9 ± 5.8 cm (writing). The mean head declinations were 63.5 ± 12.2 deg (video games), 37.1 ± 12.8 deg (reading), and 44.5 ± 14.1 deg (writing). Working distance decreased significantly across time for the reading and writing tasks (p < 0.001). Head declination increased significantly across time only for the reading task (p < 0.001). Grade level significantly influenced working distance, but the difference was not significant when working distance was adjusted by the subject’s size. No differences were observed within the refractive or the accommodative lag groups in terms of the posture data (p > 0.05). Working distance was negatively correlated with head declination (r = −0.53, p < 0.001). Conclusions Close working distances were observed for Chinese myopic schoolchildren. The attention dedicated to each task, the task difficulty, and the page/screen size may affect near working distance and head declination. Handheld video games were associated with the closest working distance, which may be a risk factor for myopia progression, according to previous studies. PMID:26107025

Approximating the Generalized Voronoi Diagram of Closely Spaced Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, John; Daniel, Eric; Pascucci, Valerio

2015-06-22

We present an algorithm to compute an approximation of the generalized Voronoi diagram (GVD) on arbitrary collections of 2D or 3D geometric objects. In particular, we focus on datasets with closely spaced objects; GVD approximation is expensive and sometimes intractable on these datasets using previous algorithms. With our approach, the GVD can be computed using commodity hardware even on datasets with many, extremely tightly packed objects. Our approach is to subdivide the space with an octree that is represented with an adjacency structure. We then use a novel adaptive distance transform to compute the distance function on octree vertices. Themore » computed distance field is sampled more densely in areas of close object spacing, enabling robust and parallelizable GVD surface generation. We demonstrate our method on a variety of data and show example applications of the GVD in 2D and 3D.« less

The relationship of maternal work characteristics to childcare type and quality in rural communities

PubMed Central

De Marco, Allison; Crouter, Ann C.; Vernon-Feagans, Lynne

2010-01-01

Drawing on data from the Family Life Project collected in North Carolina and Pennsylvania, this paper examines the relationship between maternal work characteristics and childcare type and quality in rural communities. Research is limited on the childcare experiences of rural families. Rural areas have less access to formal childcare and families often commute long distances for work, restricting childcare options. Employed mothers using childcare were selected (n = 441). Logistic and OLS regression was used to examine which characteristics, including workplace support, objective occupational measures, hours, wage, and shift, predicted care type and quality. Results indicated that most families were using informal care. Those with more hazardous work conditions and working night shifts were less likely to use centers. Higher quality care was related to more workplace support, center use, and higher wages. Implications for social policy and practice are discussed. PMID:20664710

Assessing nursing clinical skills competence through objective structured clinical examination (OSCE) for open distance learning students in Open University Malaysia.

PubMed

Oranye, Nelson Ositadimma; Ahmad, Che'an; Ahmad, Nora; Bakar, Rosnida Abu

2012-06-01

The objective structured clinical skills examination (OSCE) has over the years emerged as a method of evaluating clinical skills in most medical and allied professions. Although its validity and objectivity has evoked so much debate in the literature, little has been written about its application in non-traditional education systems such as in distance learning. This study examined clinical skills competence among practising nursing students who were enrolled in a distance learning programme. The study examined the effect of work and years of nursing practice on nurses' clinical skills competence. This study used observational design whereby nursing students' clinical skills were observed and scored in five OSCE stations. Two instruments were used for the data collection - A self-administered questionnaire on the students' bio-demographic data, and a check list on the clinical skills which the examiners rated on a four point scale. The findings revealed that 14% of the nurses had level four competence, which indicated that they could perform the tasks correctly and complete. However, 12% failed the OSCE, even though they had more than 10 years experience in nursing and post basic qualifications. Inter-rater reliability was 0.92 for the five examiners. Factor analysis indicated that five participant factors accounted for 74.1% of the variations in clinical skills performance. An OSCE is a necessary assessment tool that should be continuously applied in nursing education, regardless of the mode of the education program, the student's years of experience or his/her clinical placement. This study validates the need for OSCE in both the design of tertiary nursing degree programs and the assessment of nurses' clinical competency level.

Measuring Distances Using Digital Cameras

ERIC Educational Resources Information Center

Kendal, Dave

2007-01-01

This paper presents a generic method of calculating accurate horizontal and vertical object distances from digital images taken with any digital camera and lens combination, where the object plane is parallel to the image plane or tilted in the vertical plane. This method was developed for a project investigating the size, density and spatial…

Online Medical Diagnosis and Training in Rural Mongolia

ERIC Educational Resources Information Center

Amarsaikhan, Dashtseren; Lkhagvasuren, Tserenkhuu; Oyun, Sanjaa; Batchuluun, Batpurev

2007-01-01

This article has two major objectives. Firstly, the need for distance education (DE) in Mongolia's health sector is examined. A project is reported with the general objective of initiating research, development, and experimentation in distance-based medical diagnosis and consultancy, and in DE for rural medical doctors using Internet-based…

Study on the Implementation of Interaction Teaching Mode in Distance Education

ERIC Educational Resources Information Center

Zhou, Chunyu; Xu, Zhenhui

2015-01-01

By analyzing the learning characteristics of learners and the features of interactive teaching in distance education, this paper proposes the curriculum implementation subject of network education, namely objects multi-directional interaction teaching mode, so as to improve teaching effectiveness and achieve teaching objectives to ensure the…

Role of Libraries in Distance Education. SPEC Kit 216.

ERIC Educational Resources Information Center

Snyder, Carolyn A., Comp.; And Others

The Systems and Procedures Exchange Center (SPEC) surveyed 119 Association of Research Libraries (ARL) members to gather information about current distance education and distance learning initiatives in ARL libraries. The objectives of the survey were to: (1) identify libraries involved in distance education activities and determine the extent or…

Myopia prevention, near work, and visual acuity of college students: integrating the theory of planned behavior and self-determination theory.

PubMed

Chan, Derwin King-Chung; Fung, Ying-Ki; Xing, Suxuan; Hagger, Martin S

2014-06-01

There has been little research examining the psychological antecedents of safety-oriented behavior aimed at reducing myopia risk. This study utilizes self-determination theory (SDT) and the theory of planned behavior (TPB) to understand the role of motivational and social-cognitive factors on individuals' near-work behavior. Adopting a prospective design, undergraduate students (n = 107) completed an initial questionnaire based on SDT in week 1, a second questionnaire containing measures of TPB variables in week 2, and objective measures of reading distance and visual acuity in week 6. The data were analyzed by variance-based structural equation modeling. The results showed that perceived autonomy support and autonomous motivation from SDT significantly predicted attitude, subjective norm, and perceived behavioral control from the TPB. These social-cognitive factors were significantly associated with intention and intention significantly predicted reading distance. The relationships in the model held when controlling for visual acuity. In conclusion, the integrated model of SDT and the TPB may help explain myopia-preventive behaviors.

Conformational space annealing scheme in the inverse design of functional materials

NASA Astrophysics Data System (ADS)

Kim, Sunghyun; Lee, In-Ho; Lee, Jooyoung; Oh, Young Jun; Chang, Kee Joo

2015-03-01

Recently, the so-called inverse method has drawn much attention, in which specific electronic properties are initially assigned and target materials are subsequently searched. In this work, we develop a new scheme for the inverse design of functional materials, in which the conformational space annealing (CSA) algorithm for global optimization is combined with first-principles density functional calculations. To implement the CSA, we need a series of ingredients, (i) an objective function to minimize, (ii) a 'distance' measure between two conformations, (iii) a local enthalpy minimizer of a given conformation, (iv) ways to combine two parent conformations to generate a daughter one, (v) a special conformation update scheme, and (vi) an annealing method in the 'distance' parameter axis. We show the results of applications for searching for Si crystals with direct band gaps and the lowest-enthalpy phase of boron at a finite pressure and discuss the efficiency of the present scheme. This work is supported by the National Research Foundation of Korea (NRF) under Grant No. NRF-2005-0093845 and by Samsung Science and Technology Foundation under Grant No. SSTFBA1401-08.

A fuzzy automated object classification by infrared laser camera

NASA Astrophysics Data System (ADS)

Kanazawa, Seigo; Taniguchi, Kazuhiko; Asari, Kazunari; Kuramoto, Kei; Kobashi, Syoji; Hata, Yutaka

2011-06-01

Home security in night is very important, and the system that watches a person's movements is useful in the security. This paper describes a classification system of adult, child and the other object from distance distribution measured by an infrared laser camera. This camera radiates near infrared waves and receives reflected ones. Then, it converts the time of flight into distance distribution. Our method consists of 4 steps. First, we do background subtraction and noise rejection in the distance distribution. Second, we do fuzzy clustering in the distance distribution, and form several clusters. Third, we extract features such as the height, thickness, aspect ratio, area ratio of the cluster. Then, we make fuzzy if-then rules from knowledge of adult, child and the other object so as to classify the cluster to one of adult, child and the other object. Here, we made the fuzzy membership function with respect to each features. Finally, we classify the clusters to one with the highest fuzzy degree among adult, child and the other object. In our experiment, we set up the camera in room and tested three cases. The method successfully classified them in real time processing.

Design for robustness of unique, multi-component engineering systems

NASA Astrophysics Data System (ADS)

Shelton, Kenneth A.

2007-12-01

The purpose of this research is to advance the science of conceptual designing for robustness in unique, multi-component engineering systems. Robustness is herein defined as the ability of an engineering system to operate within a desired performance range even if the actual configuration has differences from specifications within specified tolerances. These differences are caused by three sources, namely manufacturing errors, system degradation (operational wear and tear), and parts availability. Unique, multi-component engineering systems are defined as systems produced in unique or very small production numbers. They typically have design and manufacturing costs on the order of billions of dollars, and have multiple, competing performance objectives. Design time for these systems must be minimized due to competition, high manpower costs, long manufacturing times, technology obsolescence, and limited available manpower expertise. Most importantly, design mistakes cannot be easily corrected after the systems are operational. For all these reasons, robustness of these systems is absolutely critical. This research examines the space satellite industry in particular. Although inherent robustness assurance is absolutely critical, it is difficult to achieve in practice. The current state of the art for robustness in the industry is to overdesign components and subsystems with redundancy and margin. The shortfall is that it is not known if the added margins were either necessary or sufficient given the risk management preferences of the designer or engineering system customer. To address this shortcoming, new assessment criteria to evaluate robustness in design concepts have been developed. The criteria are comprised of the "Value Distance", addressing manufacturing errors and system degradation, and "Component Distance", addressing parts availability. They are based on an evolutionary computation format that uses a string of alleles to describe the components in the design concept. These allele values are unitless themselves, but map to both configuration descriptions and attribute values. The Value Distance and Component Distance are metrics that measure the relative differences between two design concepts using the allele values, and all differences in a population of design concepts are calculated relative to a reference design, called the "base design". The base design is the top-ranked member of the population in weighted terms of robustness and performance. Robustness is determined based on the change in multi-objective performance as Value Distance and Component Distance (and thus differences in design) increases. It is assessed as acceptable if differences in design configurations up to specified tolerances result in performance changes that remain within a specified performance range. The design configuration difference tolerances and performance range together define the designer's risk management preferences for the final design concepts. Additionally, a complementary visualization capability was developed, called the "Design Solution Topography". This concept allows the visualization of a population of design concepts, and is a 3-axis plot where each point represents an entire design concept. The axes are the Value Distance, Component Distance and Performance Objective. The key benefit of the Design Solution Topography is that it allows the designer to visually identify and interpret the overall robustness of the current population of design concepts for a particular performance objective. In a multi-objective problem, each performance objective has its own Design Solution Topography view. These new concepts are implemented in an evolutionary computation-based conceptual designing method called the "Design for Robustness Method" that produces robust design concepts. The design procedures associated with this method enable designers to evaluate and ensure robustness in selected designs that also perform within a desired performance range. The method uses an evolutionary computation-based procedure to generate populations of large numbers of alternative design concepts, which are assessed for robustness using the Value Distance, Component Distance and Design Solution Topography procedures. The Design for Robustness Method provides a working conceptual designing structure in which to implement and gain the benefits of these new concepts. In the included experiments, the method was used on several mathematical examples to demonstrate feasibility, which showed favorable results as compared to existing known methods. Furthermore, it was tested on a real-world satellite conceptual designing problem to illustrate the applicability and benefits to industry. Risk management insights were demonstrated for the robustness-related issues of manufacturing errors, operational degradation, parts availability, and impacts based on selections of particular types of components.

Nasendoscopy: an analysis of measurement uncertainties.

PubMed

Gilleard, Onur; Sommerlad, Brian; Sell, Debbie; Ghanem, Ali; Birch, Malcolm

2013-05-01

Objective : The purpose of this study was to analyze the optical characteristics of two different nasendoscopes used to assess velopharyngeal insufficiency and to quantify the measurement uncertainties that will occur in a typical set of clinical data. Design : The magnification and barrel distortion associated with nasendoscopy was estimated by using computer software to analyze the apparent dimensions of a spatially calibrated test object at varying object-lens distances. In addition, a method of semiquantitative analysis of velopharyngeal closure using nasendoscopy and computer software is described. To calculate the reliability of this method, 10 nasendoscopy examinations were analyzed two times by three separate operators. The measure of intraoperator and interoperator agreement was evaluated using Pearson's r correlation coefficient. Results : Over an object lens distance of 9 mm, magnification caused the visualized dimensions of the test object to increase by 80%. In addition, dimensions of objects visualized in the far-peripheral field of the nasendoscopic examinations appeared approximately 40% smaller than those visualized in the central field. Using computer software to analyze velopharyngeal closure, the mean correlation coefficient for intrarater reliability was .94 and for interrater reliability was .90. Conclusion : Using a custom-designed apparatus, the effect object-lens distance has on the magnification of nasendoscopic images has been quantified. Barrel distortion has also been quantified and was found to be independent of object-lens distance. Using computer software to analyze clinical images, the intraoperator and interoperator correlation appears to show that ratio-metric measurements are reliable.

Detecting Intramolecular Conformational Dynamics of Single Molecules in Short Distance Range with Sub-Nanometer Sensitivity

PubMed Central

Zhou, Ruobo; Kunzelmann, Simone; Webb, Martin R.; Ha, Taekjip

2011-01-01

Single molecule detection is useful for characterizing nanoscale objects such as biological macromolecules, nano-particles and nano-devices with nano-meter spatial resolution. Fluorescence resonance energy transfer (FRET) is widely used as a single-molecule assay to monitor intramolecular dynamics in the distance range of 3–8 nm. Here we demonstrate that self-quenching of two rhodamine derivatives can be used to detect small conformational dynamics corresponding to sub-nanometer distance changes in a FRET-insensitive short range at the single molecule level. A ParM protein mutant labeled with two rhodamines works as a single molecule ADP sensor which has 20 times brighter fluorescence signal in the ADP bound state than the unbound state. Single molecule time trajectories show discrete transitions between fluorescence on and off states that can be directly ascribed to ADP binding and dissociation events. The conformational changes observed with 20:1 contrast are only 0.5 nm in magnitude and are between crystallographic distances of 1.6 nm and 2.1 nm, demonstrating exquisite sensitivity to short distance scale changes. The systems also allowed us to gain information on the photophysics of self-quenching induced by rhodamine stacking: (1) photobleaching of either of the two rhodamines eliminates quenching of the other rhodamine fluorophore and (2) photobleaching from the highly quenched, stacked state is only two-fold slower than from the unstacked state. PMID:22023515

Object-based warping: an illusory distortion of space within objects.

PubMed

Vickery, Timothy J; Chun, Marvin M

2010-12-01

Visual objects are high-level primitives that are fundamental to numerous perceptual functions, such as guidance of attention. We report that objects warp visual perception of space in such a way that spatial distances within objects appear to be larger than spatial distances in ground regions. When two dots were placed inside a rectangular object, they appeared farther apart from one another than two dots with identical spacing outside of the object. To investigate whether this effect was object based, we measured the distortion while manipulating the structure surrounding the dots. Object displays were constructed with a single object, multiple objects, a partially occluded object, and an illusory object. Nonobject displays were constructed to be comparable to object displays in low-level visual attributes. In all cases, the object displays resulted in a more powerful distortion of spatial perception than comparable non-object-based displays. These results suggest that perception of space within objects is warped.

Distance underestimation in virtual space is sensitive to gender but not activity-passivity or mode of interaction.

PubMed

Foreman, Nigel; Sandamas, George; Newson, David

2004-08-01

Four groups of undergraduates (half of each gender) experienced a movement along a corridor containing three distinctive objects, in a virtual environment (VE) with wide-screen projection. One group simulated walking along the virtual corridor using a proprietary step-exercise device. A second group moved along the corridor in conventional flying mode, depressing a keyboard key to initiate continuous forward motion. Two further groups observed the walking and flying participants, by viewing their progress on the screen. Participants then had to walk along a real equivalent but empty corridor, and indicate the positions of the three objects. All groups underestimated distances in the real corridor, the greatest underestimates occurring for the middle distance object. Males' underestimations were significantly lower than females' at all distances. However, there was no difference between the active participants and passive observers, nor between walking and flying conditions.

Mortise terrorism on the main pipelines

NASA Astrophysics Data System (ADS)

Komarov, V. A.; Nigrey, N. N.; Bronnikov, D. A.; Nigrey, A. A.

2018-01-01

The research aim of the work is to analyze the effectiveness of the methods of physical protection of main pipelines proposed in the article from the "mortise terrorism" A mathematical model has been developed that made it possible to predict the dynamics of "mortise terrorism" in the short term. An analysis of the effectiveness of physical protection methods proposed in the article to prevent unauthorized impacts on the objects under investigation is given. A variant of a video analytics system has been developed that allows detecting violators with recognition of the types of work they perform at a distance of 150 meters in conditions of complex natural backgrounds and precipitation. Probability of detection is 0.959.

Perceptual distance and the moon illusion.

PubMed

Kaufman, Lloyd; Vassiliades, Vassias; Noble, Richard; Alexander, Robert; Kaufman, James; Edlund, Stefan

2007-01-01

The elevated moon usually appears smaller than the horizon moon of equal angular size. This is the moon illusion. Distance cues may enable the perceptual system to place the horizon moon at an effectively greater distance than the elevated moon, thus making it appear as larger. This explanation is related to the size-distance invariance hypothesis. However, the larger horizon moon is usually judged as closer than the smaller zenith moon. A bias to expect an apparently large object to be closer than a smaller object may account for this conflict. We designed experiments to determine if unbiased sensitivity to illusory differences in the size and distance of the moon (as measured by d') is consistent with SDIH. A moon above a 'terrain' was compared in both distance and size to an infinitely distant moon in empty space (the reduction moon). At a short distance the terrain moon was adjudged as both closer and smaller than the reduction moon. But these differences could not be detected at somewhat greater distances. At still greater distances the terrain moon was perceived as both more distant and larger than the reduction moon. The distances at which these transitions occurred were essentially the same for both distance and size discrimination tasks, thus supporting SDIH.

Automated working distance adjustment for a handheld OCT-Laryngoscope

NASA Astrophysics Data System (ADS)

Donner, Sabine; Bleeker, Sebastian; Ripken, Tammo; Krueger, Alexander

2014-03-01

Optical coherence tomography (OCT) is an imaging technique which enables diagnosis of vocal cord tissue structure by non-contact optical biopsies rather than invasive tissue biopsies. For diagnosis on awake patients OCT was adapted to a rigid indirect laryngoscope. The working distance must match the probe-sample distance, which varies from patient to patient. Therefore the endoscopic OCT sample arm has a variable working distance of 40 mm to 80 mm. The current axial position is identified by automated working distance adjustments based on image processing. The OCT reference plane and the focal plane of the sample arm are moved according to position errors. Repeated position adjustment during the whole diagnostic procedure keeps the tissue sample at the optimal axial position. The auto focus identifies and adjusts the working distance within the range of 50 mm within a maximum time of 2.7 s. Continuous image stabilisation reduces axial sample movement within the sampling depth for handheld OCT scanning. Rapid autofocus reduces the duration of the diagnostic procedure and axial position stabilisation eases the use of the OCT laryngoscope. Therefore this work is an important step towards the integration of OCT into indirect laryngoscopes.

Lifelong Learning & Distance Higher Education. Perspectives on Distance Education

ERIC Educational Resources Information Center

McIntosh, Christopher, Ed.

2005-01-01

Reflecting a common objective of ensuring quality Education for All, this book is a joint initiative of UNESCO and COL and jointly published. Lifelong Learning in Distance Higher Education brings together a diverse group of experts from many countries. The book provides a clear picture of the challenges, problems and potential of distance higher…

The Semantic Distance Task: Quantifying Semantic Distance with Semantic Network Path Length

ERIC Educational Resources Information Center

Kenett, Yoed N.; Levi, Effi; Anaki, David; Faust, Miriam

2017-01-01

Semantic distance is a determining factor in cognitive processes, such as semantic priming, operating upon semantic memory. The main computational approach to compute semantic distance is through latent semantic analysis (LSA). However, objections have been raised against this approach, mainly in its failure at predicting semantic priming. We…

The fundamentals of average local variance--Part II: Sampling simple regular patterns with optical imagery.

PubMed

Bøcher, Peder Klith; McCloy, Keith R

2006-02-01

In this investigation, the characteristics of the average local variance (ALV) function is investigated through the acquisition of images at different spatial resolutions of constructed scenes of regular patterns of black and white squares. It is shown that the ALV plot consistently peaks at a spatial resolution in which the pixels has a size corresponding to half the distance between scene objects, and that, under very specific conditions, it also peaks at a spatial resolution in which the pixel size corresponds to the whole distance between scene objects. It is argued that the peak at object distance when present is an expression of the Nyquist sample rate. The presence of this peak is, hence, shown to be a function of the matching between the phase of the scene pattern and the phase of the sample grid, i.e., the image. When these phases match, a clear and distinct peak is produced on the ALV plot. The fact that the peak at half the distance consistently occurs in the ALV plot is linked to the circumstance that the sampling interval (distance between pixels) and the extent of the sampling unit (size of pixels) are equal. Hence, at twice the Nyquist sampling rate, each fundamental period of the pattern is covered by four pixels; therefore, at least one pixel is always completely embedded within one pattern element, regardless of sample scene phase. If the objects in the scene are scattered with a distance larger than their extent, the peak will be related to the size by a factor larger than 1/2. This is suggested to be the explanation to the results presented by others that the ALV plot is related to scene-object size by a factor of 1/2-3/4.

Streaming of Continuous Media for Distance Education Systems

ERIC Educational Resources Information Center

Dashti, Ali; Safar, Maytham

2007-01-01

Distance education created new challenges regarding the delivery of large size isochronous continuous streaming media (SM) objects. In this paper, we consider the design of a framework for customized SM presentations, where each presentation consists of a number of SM objects that should be retrieved and displayed to the user in a coherent…

Self-regulating flow control device

DOEpatents

Humphreys, Duane A.

1984-01-01

A variable, self-regulating valve having a hydraulic loss coefficient proportional to a positive exponential power of the flow rate. The device includes two objects in a flow channel and structure which assures that the distance between the two objects is an increasing function of the flow rate. The range of spacing between the objects is such that the hydraulic resistance of the valve is an increasing function of the distance between the two objects so that the desired hydraulic loss coefficient as a function of flow rate is obtained without variation in the flow area.

Self-regulating valve

DOEpatents

Humphreys, D.A.

1982-07-20

A variable, self-regulating valve having a hydraulic loss coefficient proportional to a positive exponential power of the flow rate. The device includes two objects in a flow channel and structure which assures that the distance between the two objects is an increasing function of the flow rate. The range of spacing between the objects is such that the hydraulic resistance of the valve is an increasing function of the distance between the two objects so that the desired hydraulic loss coefficient as a function of flow rate is obtained without variation in the flow area.

Application of digital image correlation for long-distance bridge deflection measurement

NASA Astrophysics Data System (ADS)

Tian, Long; Pan, Bing; Cai, Youfa; Liang, Hui; Zhao, Yan

2013-06-01

Due to its advantages of non-contact, full-field and high-resolution measurement, digital image correlation (DIC) method has gained wide acceptance and found numerous applications in the field of experimental mechanics. In this paper, the application of DIC for real-time long-distance bridge deflection detection in outdoor environments is studied. Bridge deflection measurement using DIC in outdoor environments is more challenging than regular DIC measurements performed under laboratory conditions. First, much more image noise due to variations in ambient light will be presented in the images recorded in outdoor environments. Second, how to select the target area becomes a key factor because long-distance imaging results in a large field of view of the test object. Finally, the image acquisition speed of the camera must be high enough (larger than 100 fps) to capture the real-time dynamic motion of a bridge. In this work, the above challenging issues are addressed and several improvements were made to DIC method. The applicability was demonstrated by real experiments. Experimental results indicate that the DIC method has great potentials in motion measurement in various large building structures.

Identification and detection of simple 3D objects with severely blurred vision.

PubMed

Kallie, Christopher S; Legge, Gordon E; Yu, Deyue

2012-12-05

Detecting and recognizing three-dimensional (3D) objects is an important component of the visual accessibility of public spaces for people with impaired vision. The present study investigated the impact of environmental factors and object properties on the recognition of objects by subjects who viewed physical objects with severely reduced acuity. The experiment was conducted in an indoor testing space. We examined detection and identification of simple convex objects by normally sighted subjects wearing diffusing goggles that reduced effective acuity to 20/900. We used psychophysical methods to examine the effect on performance of important environmental variables: viewing distance (from 10-24 feet, or 3.05-7.32 m) and illumination (overhead fluorescent and artificial window), and object variables: shape (boxes and cylinders), size (heights from 2-6 feet, or 0.61-1.83 m), and color (gray and white). Object identification was significantly affected by distance, color, height, and shape, as well as interactions between illumination, color, and shape. A stepwise regression analysis showed that 64% of the variability in identification could be explained by object contrast values (58%) and object visual angle (6%). When acuity is severely limited, illumination, distance, color, height, and shape influence the identification and detection of simple 3D objects. These effects can be explained in large part by the impact of these variables on object contrast and visual angle. Basic design principles for improving object visibility are discussed.

Visual Mislocalization of Moving Objects in an Audiovisual Event.

PubMed

Kawachi, Yousuke

2016-01-01

The present study investigated the influence of an auditory tone on the localization of visual objects in the stream/bounce display (SBD). In this display, two identical visual objects move toward each other, overlap, and then return to their original positions. These objects can be perceived as either streaming through or bouncing off each other. In this study, the closest distance between object centers on opposing trajectories and tone presentation timing (none, 0 ms, ± 90 ms, and ± 390 ms relative to the instant for the closest distance) were manipulated. Observers were asked to judge whether the two objects overlapped with each other and whether the objects appeared to stream through, bounce off each other, or reverse their direction of motion. A tone presented at or around the instant of the objects' closest distance biased judgments toward "non-overlapping," and observers overestimated the physical distance between objects. A similar bias toward direction change judgments (bounce and reverse, not stream judgments) was also observed, which was always stronger than the non-overlapping bias. Thus, these two types of judgments were not always identical. Moreover, another experiment showed that it was unlikely that this observed mislocalization could be explained by other previously known mislocalization phenomena (i.e., representational momentum, the Fröhlich effect, and a turn-point shift). These findings indicate a new example of crossmodal mislocalization, which can be obtained without temporal offsets between audiovisual stimuli. The mislocalization effect is also specific to a more complex stimulus configuration of objects on opposing trajectories, with a tone that is presented simultaneously. The present study promotes an understanding of relatively complex audiovisual interactions beyond simple one-to-one audiovisual stimuli used in previous studies.

Distance to Dark Bodies

NASA Technical Reports Server (NTRS)

2007-01-01

Using the unique orbit of NASA's Spitzer Space Telescope and a depth-perceiving trick called parallax, astronomers have determined the distance to an invisible Milky Way object called OGLE-2005-SMC-001. This artist's concept illustrates how this trick works: different views from both Spitzer and telescopes on Earth are combined to give depth perception.

Our Milky Way galaxy is heavier than it looks, and scientists use the term 'dark matter' to describe all the 'heavy stuff' in the universe that seems to be present but invisible to our telescopes. While much of this dark matter is likely made up of exotic materials, different from the ordinary particles that make up the world around us, some may consist of dark celestial bodies -- like planets, black holes, or failed stars -- that do not produce light or are too faint to detect from Earth. OGLE-2005-SMC-001 is one of these dark celestial bodies.

Although astronomers cannot see a dark body, they can sense its presence from the way light acts around it. When a dark body like OGLE-2005-SMC-001 passes in front of a bright star, its gravity causes the background starlight to bend and brighten, a process called gravitational microlensing. When the observing telescope, dark body, and star system are closely aligned, the microlensing event reaches maximum, or peak, brightness.

A team of astronomers first sensed OGLE-2005-SMC-001's presence when it passed in front of a star in a neighboring satellite galaxy called the Small Magellanic Cloud. In this artist's rendering, the satellite galaxy is depicted as the fuzzy structure sitting to the left of Earth. Once they detected this microlensing event, the scientists used Spitzer and the principle of parallax to figure out its distance. Humans naturally use parallax to determine distance. Each eye sees the distance of an object differently. The brain takes each eye's perspective and instantaneously calculates how far away the object is.

To determine OGLE-2005-SMC-001's distance, astronomers measured the microlensing event over several months with both Spitzer in space and the Earth-based telescopes. Careful analysis of the data revealed the time of the peak brightness differed slightly between the two locations.

Because astronomers knew the exact distance between Earth and Spitzer and the time lag between the peak-observed brightness, they could determine OGLE-2005-SMC-001's speed. Using trigonometric equations and graphs to do the 'brain's' job, scientists then inferred the dark body's location to be in the outer portion, or halo, of our galaxy.

The picture of the Small Magellanic Cloud in this concept is a two-color image from two Digitized Sky Survey 2 observations The Digitized Sky Survey is based at the Space Telescope Science Institute in Baltimore, Md.

Multi objective decision making in hybrid energy system design

NASA Astrophysics Data System (ADS)

Merino, Gabriel Guillermo

The design of grid-connected photovoltaic wind generator system supplying a farmstead in Nebraska has been undertaken in this dissertation. The design process took into account competing criteria that motivate the use of different sources of energy for electric generation. The criteria considered were 'Financial', 'Environmental', and 'User/System compatibility'. A distance based multi-objective decision making methodology was developed to rank design alternatives. The method is based upon a precedence order imposed upon the design objectives and a distance metric describing the performance of each alternative. This methodology advances previous work by combining ambiguous information about the alternatives with a decision-maker imposed precedence order in the objectives. Design alternatives, defined by the photovoltaic array and wind generator installed capacities, were analyzed using the multi-objective decision making approach. The performance of the design alternatives was determined by simulating the system using hourly data for an electric load for a farmstead and hourly averages of solar irradiation, temperature and wind speed from eight wind-solar energy monitoring sites in Nebraska. The spatial variability of the solar energy resource within the region was assessed by determining semivariogram models to krige hourly and daily solar radiation data. No significant difference was found in the predicted performance of the system when using kriged solar radiation data, with the models generated vs. using actual data. The spatial variability of the combined wind and solar energy resources was included in the design analysis by using fuzzy numbers and arithmetic. The best alternative was dependent upon the precedence order assumed for the main criteria. Alternatives with no PV array or wind generator dominated when the 'Financial' criteria preceded the others. In contrast, alternatives with a nil component of PV array but a high wind generator component, dominated when the 'Environment' objective or the 'User/System compatibility' objectives were more important than the 'Financial' objectives and they also dominated when the three criteria were considered equally important.

Changes in mode of travel to work: a natural experimental study of new transport infrastructure.

PubMed

Heinen, Eva; Panter, Jenna; Mackett, Roger; Ogilvie, David

2015-06-20

New transport infrastructure may promote a shift towards active travel, thereby improving population health. The purpose of this study was to determine the effect of a major transport infrastructure project on commuters' mode of travel, trip frequency and distance travelled to work. Quasi-experimental analysis nested within a cohort study of 470 adults working in Cambridge, UK. The intervention consisted of the opening of a guided busway with a path for walking and cycling in 2011. Exposure to the intervention was defined as the negative of the square root of the shortest distance from home to busway. The outcome measures were changes in commute mode share and number of commute trips - both based on a seven-day travel-to-work record collected before (2009) and after (2012) the intervention - and change in objective commute distance. The mode share outcomes were changes in the proportions of trips (i) involving any active travel, (ii) involving any public transport, and (iii) made entirely by car. Separate multinomial regression models were estimated adjusting for commute and sociodemographic characteristics, residential settlement size and life events. Proximity to the busway predicted an increased likelihood of a large (>30 %) increase in the share of commute trips involving any active travel (relative risk ratio [RRR] 1.80, 95 % CI 1.27, 2.55) and a large decrease in the share of trips made entirely by car (RRR 2.09, 95 % CI 1.35, 3.21), as well as a lower likelihood of a small (<30 %) reduction in the share of trips involving any active travel (RRR 0.47, 95 % CI 0.28, 0.81). It was not associated with changes in the share of commute trips involving any public transport, the number of commute trips, or commute distance. The new infrastructure promoted an increase in the share of commuting trips involving active travel and a decrease in the share made entirely by car. Further analysis will show the extent to which the changes in commute mode share were translated into an increase in time spent in active commuting and consequent health gain.

Seeing the Forest Through the Trees: The Distribution and Properties of Dense Molecular Gas in the Milky Way Galaxy

NASA Astrophysics Data System (ADS)

Ellsworth-Bowers, Timothy P.

The Milky Way Galaxy serves as a vast laboratory for studying the dynamics and evolution of the dense interstellar medium and the processes of and surrounding massive star formation. From our vantage point within the Galactic plane, however, it has been extremely difficult to construct a coherent picture of Galactic structure; we cannot see the forest for the trees. The principal difficulties in studying the structure of the Galactic disk have been obscuration by the ubiquitous dust and molecular gas and confusion between objects along a line of sight. Recent technological advances have led to large-scale blind surveys of the Galactic plane at (sub-)millimeter wavelengths, where Galactic dust is generally optically thin, and have opened a new avenue for studying the forest. The Bolocam Galactic Plane Survey (BGPS) observed over 190 deg 2 of the Galactic plane in dust continuum emission near lambda = 1.1 mm, producing a catalog of over 8,000 dense molecular cloud structures across a wide swath of the Galactic disk. Deriving the spatial distribution and physical properties of these objects requires knowledge of distance, a component lacking in the data themselves. This thesis presents a generalized Bayesian probabilistic distance estimation method for dense molecular cloud structures, and demonstrates it with the BGPS data set. Distance probability density functions (DPDFs) are computed from kinematic distance likelihoods (which may be double- peaked for objects in the inner Galaxy) and an expandable suite of prior information to produce a comprehensive tally of our knowledge (and ignorance) of the distances to dense molecular cloud structures. As part of the DPDF formalism, this thesis derives several prior DPDFs for resolving the kinematic distance ambiguity in the inner Galaxy. From the collection of posterior DPDFs, a set of objects with well-constrained distance estimates is produced for deriving Galactic structure and the physical properties of dense molecular cloud structures. This distance catalog of 1,802 objects across the Galactic plane represents the first large-scale analysis of clump-scale objects in a variety of Galactic environments. The Galactocentric positions of these objects begin to trace out the spiral structure of the Milky Way, and suggest that dense molecular gas settles nearer the Galactic midplane than tracers of less-dense gas such as CO. Physical properties computed from the DPDFs reveal that BGPS objects trace a continuum of scales within giant molecular clouds, and extend the scaling relationships known as Larson's Laws to lower-mass substructures. The results presented here represent the first step on the road to seeing the molecular content of the Milky Way as a forest rather than individual nearby trees.

The visual perception of size and distance.

DOT National Transportation Integrated Search

1962-07-01

The perception of absolute distance has been assumed to be important in the perception of the size of objects and the depth between them. A different hypothesis is proposed. It is asserted that perceived relative size and distance are the primary psy...

Resolution and quality enhancement in terahertz in-line holography by sub-pixel sampling with double-distance reconstruction.

PubMed

Li, Zeyu; Li, Lei; Qin, Yu; Li, Guangbin; Wang, Du; Zhou, Xun

2016-09-05

We demonstrate the enhancement of resolution and image quality in terahertz (THz) lens-free in-line digital holography by sub-pixel sampling with double-distance reconstruction. Multiple sub-pixel shifted low-resolution (LR) holograms recorded by a pyroelectric array detector (100 μm × 100 μm pixel pitch, 124 × 124 pixels) are aligned precisely to synthesize a high-resolution (HR) hologram. By this method, the lateral resolution is no more limited by the pixel pitch, and lateral resolution of 150 μm is obtained, which corresponds to 1.26λ with respect to the illuminating wavelength of 118.8 μm (2.52 THz). Compared with other published works, to date, this is the highest resolution in THz digital holography when considering the illuminating wavelength. In addition, to suppress the twin-image and zero-order artifacts, the complex amplitude distributions of both object and illuminaing background wave fields are reconstructed simultaneously. This is achieved by iterative phase retrieval between the double HR holograms and background images at two recording planes, which does not require any constraints on object plane or a priori knowledge of the sample.

Neural Decoding and "Inner" Psychophysics: A Distance-to-Bound Approach for Linking Mind, Brain, and Behavior.

PubMed

Ritchie, J Brendan; Carlson, Thomas A

2016-01-01

A fundamental challenge for cognitive neuroscience is characterizing how the primitives of psychological theory are neurally implemented. Attempts to meet this challenge are a manifestation of what Fechner called "inner" psychophysics: the theory of the precise mapping between mental quantities and the brain. In his own time, inner psychophysics remained an unrealized ambition for Fechner. We suggest that, today, multivariate pattern analysis (MVPA), or neural "decoding," methods provide a promising starting point for developing an inner psychophysics. A cornerstone of these methods are simple linear classifiers applied to neural activity in high-dimensional activation spaces. We describe an approach to inner psychophysics based on the shared architecture of linear classifiers and observers under decision boundary models such as signal detection theory. Under this approach, distance from a decision boundary through activation space, as estimated by linear classifiers, can be used to predict reaction time in accordance with signal detection theory, and distance-to-bound models of reaction time. Our "neural distance-to-bound" approach is potentially quite general, and simple to implement. Furthermore, our recent work on visual object recognition suggests it is empirically viable. We believe the approach constitutes an important step along the path to an inner psychophysics that links mind, brain, and behavior.

Identifying the driving forces of urban expansion and its environmental impact in Jakarta-Bandung mega urban region

NASA Astrophysics Data System (ADS)

Pravitasari, A. E.; Rustiadi, E.; Mulya, S. P.; Setiawan, Y.; Fuadina, L. N.; Murtadho, A.

2018-05-01

The socio-economic development in Jakarta-Bandung Mega Urban Region (JBMUR) caused the increasing of urban expansion and led to a variety of environmental damage such as uncontrolled land use conversion and raising anthropogenic disaster. The objectives of this study are: (1) to identify the driving forces of urban expansion that occurs on JBMUR and (2) to analyze the environmental quality decline on JBMUR by producing time series spatial distribution map and spatial autocorrelation of floods and landslide as the proxy of anthropogenic disaster. The driving forces of urban expansion in this study were identified by employing Geographically Weighted Regression (GWR) model using 6 (six) independent variables, namely: population density, percentage of agricultural land, distance to the center of capital city/municipality, percentage of household who works in agricultural sector, distance to the provincial road, and distance to the local road. The GWR results showed that local demographic, social and economic factors including distance to the road spatially affect urban expansion in JBMUR. The time series spatial distribution map of floods and landslide event showed the spatial cluster of anthropogenic disaster in some areas. Through Local Moran Index, we found that environmental damage in one location has a significant impact on the condition of its surrounding area.

Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

PubMed Central

Luna, Natália Mariana Silva; Alonso, Angelica Castilho; Brech, Guilherme Carlos; Mochizuki, Luis; Nakano, Eduardo Yoshio; Greve, Júlia Maria D'Andréa

2012-01-01

OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and non-athletes. METHODS: Seventy-five males with a mean age of 30.26 (±6.5) years were divided into three groups: a triathlete group (n = 26), a long-distance runner group (n = 23), and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. RESULTS: The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180°/s) was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60°/s) was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. CONCLUSIONS: The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners. PMID:23018298

Apparent minification in an imaging display under reduced viewing conditions.

PubMed

Meehan, J W

1993-01-01

When extended outdoor scenes are imaged with magnification of 1 in optical, electronic, or computer-generated displays, scene features appear smaller and farther than in direct view. This has been shown to occur in various periscopic and camera-viewfinder displays outdoors in daylight. In four experiments it was found that apparent minification of the size of a planar object at a distance of 3-9 m indoors occurs in the viewfinder display of an SLR camera both in good light and in darkness with only the luminous object visible. The effect is robust and survives changes in the relationship between object luminance in the display and in direct view and occurs in the dark when subjects have no prior knowledge of room dimensions, object size or object distance. The results of a fifth experiment suggest that the effect is an instance of reduced visual size constancy consequent on elimination of cues for size, which include those for distance.

Analyzing the Quality of Students Interaction in a Distance Learning Object-Oriented Programming Discipline

ERIC Educational Resources Information Center

Carvalho, Elizabeth Simão

2015-01-01

Teaching object-oriented programming to students in an in-classroom environment demands well-thought didactic and pedagogical strategies in order to guarantee a good level of apprenticeship. To teach it on a completely distance learning environment (e-learning) imposes possibly other strategies, besides those that the e-learning model of Open…

Supporting Distance Learners for Collaborative Problem Solving.

ERIC Educational Resources Information Center

Verdejo, M. F.; Barros, B.; Abad, M. T.

This paper describes a computer-supported environment designed to facilitate distance learning through collaborative problem-solving. The goal is to encourage distance learning students to work together, in order to promote both learning of collaboration and learning through collaboration. Collaboration is defined as working together on a common…

[The forensic medical characteristic of the factors associated with a shot from the 9.0 mm pneumatic rifle and the inflicted injuries].

PubMed

Raĭzberg, S A; Makarov, I Iu; Lorents, A S

2014-01-01

The objective of the present work was to elucidate the structural characteristics of the 9.0 mm pneumatic rifle and three regular types of the bullets differing in the head shape fired from it. Morphological features of the injuries inflicted by such bullets are described in conjunction with the peculiarities of precipitation of the shot products in their projection as the prerequisites for their objective differentiation. Results: The study allowed to reveal the composition of the gunshot residues and to determine the maximum distance of their distribution. The specific features of experimental damage inflicted by the shots from the 9.0 mm pneumatic rifle to the coarse white calico fabric targets were shown to depend on the shot range. The objective signs of the so-called "short-range" shot from the 9.0 mm pneumatic rifle were described for the first time.

Heterodyne laser Doppler distance sensor with phase coding measuring stationary as well as laterally and axially moving objects

NASA Astrophysics Data System (ADS)

Pfister, T.; Günther, P.; Nöthen, M.; Czarske, J.

2010-02-01

Both in production engineering and process control, multidirectional displacements, deformations and vibrations of moving or rotating components have to be measured dynamically, contactlessly and with high precision. Optical sensors would be predestined for this task, but their measurement rate is often fundamentally limited. Furthermore, almost all conventional sensors measure only one measurand, i.e. either out-of-plane or in-plane distance or velocity. To solve this problem, we present a novel phase coded heterodyne laser Doppler distance sensor (PH-LDDS), which is able to determine out-of-plane (axial) position and in-plane (lateral) velocity of rough solid-state objects simultaneously and independently with a single sensor. Due to the applied heterodyne technique, stationary or purely axially moving objects can also be measured. In addition, it is shown theoretically as well as experimentally that this sensor offers concurrently high temporal resolution and high position resolution since its position uncertainty is in principle independent of the lateral object velocity in contrast to conventional distance sensors. This is a unique feature of the PH-LDDS enabling precise and dynamic position and shape measurements also of fast moving objects. With an optimized sensor setup, an average position resolution of 240 nm was obtained.

A hybrid genetic algorithm for solving bi-objective traveling salesman problems

NASA Astrophysics Data System (ADS)

Ma, Mei; Li, Hecheng

2017-08-01

The traveling salesman problem (TSP) is a typical combinatorial optimization problem, in a traditional TSP only tour distance is taken as a unique objective to be minimized. When more than one optimization objective arises, the problem is known as a multi-objective TSP. In the present paper, a bi-objective traveling salesman problem (BOTSP) is taken into account, where both the distance and the cost are taken as optimization objectives. In order to efficiently solve the problem, a hybrid genetic algorithm is proposed. Firstly, two satisfaction degree indices are provided for each edge by considering the influences of the distance and the cost weight. The first satisfaction degree is used to select edges in a “rough” way, while the second satisfaction degree is executed for a more “refined” choice. Secondly, two satisfaction degrees are also applied to generate new individuals in the iteration process. Finally, based on genetic algorithm framework as well as 2-opt selection strategy, a hybrid genetic algorithm is proposed. The simulation illustrates the efficiency of the proposed algorithm.

Automatic Clustering Using Multi-objective Particle Swarm and Simulated Annealing

PubMed Central

Abubaker, Ahmad; Baharum, Adam; Alrefaei, Mahmoud

2015-01-01

This paper puts forward a new automatic clustering algorithm based on Multi-Objective Particle Swarm Optimization and Simulated Annealing, “MOPSOSA”. The proposed algorithm is capable of automatic clustering which is appropriate for partitioning datasets to a suitable number of clusters. MOPSOSA combines the features of the multi-objective based particle swarm optimization (PSO) and the Multi-Objective Simulated Annealing (MOSA). Three cluster validity indices were optimized simultaneously to establish the suitable number of clusters and the appropriate clustering for a dataset. The first cluster validity index is centred on Euclidean distance, the second on the point symmetry distance, and the last cluster validity index is based on short distance. A number of algorithms have been compared with the MOPSOSA algorithm in resolving clustering problems by determining the actual number of clusters and optimal clustering. Computational experiments were carried out to study fourteen artificial and five real life datasets. PMID:26132309

Exploding Stars and the Accelerating Universe

NASA Astrophysics Data System (ADS)

Kirshner, Robert P.

2012-01-01

Supernovae are exceptionally interesting astronomical objects: they punctuate the end of stellar evolution, create the heavy elements, and blast the interstellar gas with energetic shock waves. By studying supernovae, we can learn how these important aspects of cosmic evolution take place. Over the decades, we have learned that some supernovae are produced by gravitational collapse, and others by thermonuclear explosions. By understanding what supernovae are, or at least learning how they behave, supernovae explosions have been harnessed for the problem of measuring cosmic distances with some astonishing results. Carefully calibrated supernovae provide the best extragalactic distance indicators to probe the distances to galaxies and to measure the Hubble constant. Even more interesting is the evidence from supernovae that cosmic expansion has been speeding up over the last 5 billion years. We attribute this acceleration to a mysterious dark energy whose effects are clear, but whose nature is obscure. Combining the cosmic expansion history traced by supernovae with clues from galaxy clustering and cosmic geometry from the microwave background has produced today's standard, but peculiar, picture of a universe that is mostly dark energy, braked (with diminishing effect) by dark matter, and illuminated by a pinch of luminous baryons. In this talk, I will show how the attempt to understand supernovae, facilitated by ever-improving instruments, has led to the ability to measure the properties of dark energy. Looking ahead, the properties of supernovae as measured at infrared wavelengths seem to hold the best promise for more precise and accurate distances to help us understand the puzzle of dark energy. My own contribution to this work has been carried out in joyful collaboration with many excellent students, postdocs, and colleagues and with generous support from the places I have worked, the National Science Foundation, and from NASA.

Visual Mislocalization of Moving Objects in an Audiovisual Event

PubMed Central

Kawachi, Yousuke

2016-01-01

The present study investigated the influence of an auditory tone on the localization of visual objects in the stream/bounce display (SBD). In this display, two identical visual objects move toward each other, overlap, and then return to their original positions. These objects can be perceived as either streaming through or bouncing off each other. In this study, the closest distance between object centers on opposing trajectories and tone presentation timing (none, 0 ms, ± 90 ms, and ± 390 ms relative to the instant for the closest distance) were manipulated. Observers were asked to judge whether the two objects overlapped with each other and whether the objects appeared to stream through, bounce off each other, or reverse their direction of motion. A tone presented at or around the instant of the objects’ closest distance biased judgments toward “non-overlapping,” and observers overestimated the physical distance between objects. A similar bias toward direction change judgments (bounce and reverse, not stream judgments) was also observed, which was always stronger than the non-overlapping bias. Thus, these two types of judgments were not always identical. Moreover, another experiment showed that it was unlikely that this observed mislocalization could be explained by other previously known mislocalization phenomena (i.e., representational momentum, the Fröhlich effect, and a turn-point shift). These findings indicate a new example of crossmodal mislocalization, which can be obtained without temporal offsets between audiovisual stimuli. The mislocalization effect is also specific to a more complex stimulus configuration of objects on opposing trajectories, with a tone that is presented simultaneously. The present study promotes an understanding of relatively complex audiovisual interactions beyond simple one-to-one audiovisual stimuli used in previous studies. PMID:27111759

Distance education for tobacco reduction with Inuit frontline health workers

PubMed Central

Collins, Rob; Hammond, Merryl; Carry, Catherine L.; Kinnon, Dianne; Killulark, Joan; Nevala, Janet

2013-01-01

Background Tobacco reduction is a major priority in Canadian Inuit communities. However, many Inuit frontline health workers lacked the knowledge, confidence and support to address the tobacco epidemic. Given vast distances, high costs of face-to-face training and previous successful pilots using distance education, this method was chosen for a national tobacco reduction course. Objective To provide distance education about tobacco reduction to at least 25 frontline health workers from all Inuit regions of Canada. Design Promising practices globally were assessed in a literature survey. The National Inuit Tobacco Task Group guided the project. Participants were selected from across Inuit Nunangat. They chose a focus from a “menu” of 6 course options, completed a pre-test to assess individual learning needs and chose which community project(s) to complete. Course materials were mailed, and trainers provided intensive, individualized support through telephone, fax and e-mail. The course ended with an open-book post-test. Follow-up support continued for several months post-training. Results Of the 30 participants, 27 (90%) completed the course. The mean pre-test score was 72% (range: 38–98%). As the post-test was done using open books, everyone scored 100%, with a mean improvement of 28% (range: 2–62%). Conclusions Although it was often challenging to contact participants through phone, a distance education approach was very practical in a northern context. Learning is more concrete when it happens in a real-life context. As long as adequate support is provided, we recommend individualized distance education to others working in circumpolar regions. PMID:23984270

Proof of principle study of the use of a CMOS active pixel sensor for proton radiography.

PubMed

Seco, Joao; Depauw, Nicolas

2011-02-01

Proof of principle study of the use of a CMOS active pixel sensor (APS) in producing proton radiographic images using the proton beam at the Massachusetts General Hospital (MGH). A CMOS APS, previously tested for use in s-ray radiation therapy applications, was used for proton beam radiographic imaging at the MGH. Two different setups were used as a proof of principle that CMOS can be used as proton imaging device: (i) a pen with two metal screws to assess spatial resolution of the CMOS and (ii) a phantom with lung tissue, bone tissue, and water to assess tissue contrast of the CMOS. The sensor was then traversed by a double scattered monoenergetic proton beam at 117 MeV, and the energy deposition inside the detector was recorded to assess its energy response. Conventional x-ray images with similar setup at voltages of 70 kVp and proton images using commercial Gafchromic EBT 2 and Kodak X-Omat V films were also taken for comparison purposes. Images were successfully acquired and compared to x-ray kVp and proton EBT2/X-Omat film images. The spatial resolution of the CMOS detector image is subjectively comparable to the EBT2 and Kodak X-Omat V film images obtained at the same object-detector distance. X-rays have apparent higher spatial resolution than the CMOS. However, further studies with different commercial films using proton beam irradiation demonstrate that the distance of the detector to the object is important to the amount of proton scatter contributing to the proton image. Proton images obtained with films at different distances from the source indicate that proton scatter significantly affects the CMOS image quality. Proton radiographic images were successfully acquired at MGH using a CMOS active pixel sensor detector. The CMOS demonstrated spatial resolution subjectively comparable to films at the same object-detector distance. Further work will be done in order to establish the spatial and energy resolution of the CMOS detector for protons. The development and use of CMOS in proton radiography could allow in vivo proton range checks, patient setup QA, and real-time tumor tracking.

Quick-sealing design for radiological containment

DOEpatents

Rampolia, Donald S.; Speer, Elmer

1990-01-01

A quick-sealing assembly and method for forming an adhesive seal on opposite sides of a mechanical seal for a flexible containment bag of the type used for working with radioactively contaminated objects. The assembly includes an elongated mechanical fastener having opposing engaging members affixed at a predetermined distance from each of the elongated edges, with an adhesive layer formed between the mechanical fastener and the elongated edge such that upon engagement of the mechanical fastener and adhesive layers to opposing containment fabric, a neat triple hermetic seal is formed.

Quick-sealing design for radiological containment

DOEpatents

Rampolla, Donald S.; Speer, Elmer

1991-01-01

A quick-sealing assembly and method for forming an adhesive seal on opposite sides of a mechanical seal for a flexible containment bag of the type used for working with radioactively contaminated objects. The assembly includes an elongated mechanical fastener having opposing engaging members affixed at a predetermined distance from each of the elongated edges, with an adhesive layer formed between the mechanical fastener and the elongated edge such that upon engagement of the mechanical fastener and adhesive layers to opposing containment fabric, a neat triple hermetic seal is formed.

Manipulation of mammalian cells using a single-fiber optical microbeam

PubMed Central

Mohanty, Samarendra K.; Mohanty, Khyati S.; Berns, Michael W.

2014-01-01

The short working distance of microscope objectives has severely restricted the application of optical micromanipulation techniques at larger depths. We show the first use of fiber-optic tweezers toward controlled guidance of neuronal growth cones and stretching of neurons. Further, by mode locking, the fiber-optic tweezers beam was converted to fiber-optic scissors, enabling dissection of neuronal processes and thus allowing study of the subsequent response of neurons to localized injury. At high average powers, lysis of a three-dimensionally trapped cell was accomplished. PMID:19021429

Extended depth of field in an intrinsically wavefront-encoded biometric iris camera

NASA Astrophysics Data System (ADS)

Bergkoetter, Matthew D.; Bentley, Julie L.

2014-12-01

This work describes a design process which greatly increases the depth of field of a simple three-element lens system intended for biometric iris recognition. The system is optimized to produce a point spread function which is insensitive to defocus, so that recorded images may be deconvolved without knowledge of the exact object distance. This is essentially a variation on the technique of wavefront encoding, however the desired encoding effect is achieved by aberrations intrinsic to the lens system itself, without the need for a pupil phase mask.

Cooperative Learning at a Distance: An Experiment with Wikis

ERIC Educational Resources Information Center

Campbell, Katherine; Ellingson, Dee Ann

2010-01-01

The merits of incorporating group work into learning environments are well established. Online classes and other distance learning settings, however, can make it challenging to introduce traditional group projects. Wikis use technology to facilitate group work in distance learning settings. Wikis allow individuals in different locations to…

Vorticity Dynamics in Single and Multiple Swirling Reacting Jets

NASA Astrophysics Data System (ADS)

Smith, Travis; Aguilar, Michael; Emerson, Benjamin; Noble, David; Lieuwen, Tim

2015-11-01

This presentation describes an analysis of the unsteady flow structures in two multinozzle swirling jet configurations. This work is motivated by the problem of combustion instabilities in premixed flames, a major concern in the development of modern low NOx combustors. The objective is to compare the unsteady flow structures in these two configurations for two separate geometries and determine how certain parameters, primarily distance between jets, influence the flow dynamics. The analysis aims to differentiate between the flow dynamics of single nozzle and triple nozzle configurations. This study looks at how the vorticity in the shear layers of one reacting swirling jet can affect the dynamics of a nearby similar jet. The distance between the swirling jets is found to have an effect on the flow field in determining where swirling jets merge and on the dynamics upstream of the merging location. Graduate Student, School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA.

New Asymptotic Giant Branch Carbon Stars in the Galactic Halo

NASA Astrophysics Data System (ADS)

Mauron, N.; Gigoyan, K. S.; Kostandyan, G. R.

2018-03-01

For the first time the data on the eight confirmed or candidate carbon (C) stars found mainly from objective-prism plates are presented. By using the Catalina database of lightcurves, we find that all these stars are pulsating, allowing a distance to be estimated through the K-band Period-Luminosity (PL) relation. This relation does not depend on spectral type (M or C) and distances are reliable even for C candidates. Seven stars are more than 10 kpc from the galactic plane, suggesting they do not belong to the galactic disk. We also find one star located at about 180 kpc from the Sun, being one of the most distant star in the Galaxy. Many of these new C stars are relatively blue. Some comments are also provided on seven other known halo carbon stars for which either a pulsation period is obtained, or because they were not included in previous works on halo C stars.

STS-93 Flight Day 1 Highlights and Crew Activities

NASA Technical Reports Server (NTRS)

1999-01-01

On this first day of the STS-93 Columbia mission, the flight crew, Commander Eileen Collins, Pilot Jeff Ashby and Mission Specialists Cady Coleman, Steve Hawley and Michael Tognini deployed the Chandra X-Ray Observatory into space. This was done after a full night of work and preparation. Chandra will study the invisible, and often violent mysteries of x-ray astronomy. Commander Collins maneuvered Columbia to a safe distance away from the telescope as an internal timer counted down to the first of a two-phase ignition of the Inertial Upper Stage. After switching to internal battery power until its solar rays are deployed, the telescope reaches an oval orbit one-third the distance to the Moon to conduct its astronomical observations. Since Chandra is safely on its way and the major objective of their mission is successfully completed, the astronauts end their long day and begin an eight hour sleep period.

Acoustic Localization with Infrasonic Signals

NASA Astrophysics Data System (ADS)

Threatt, Arnesha; Elbing, Brian

2015-11-01

Numerous geophysical and anthropogenic events emit infrasonic frequencies (<20 Hz), including volcanoes, hurricanes, wind turbines and tornadoes. These sounds, which cannot be heard by the human ear, can be detected from large distances (in excess of 100 miles) due to low frequency acoustic signals having a very low decay rate in the atmosphere. Thus infrasound could be used for long-range, passive monitoring and detection of these events. An array of microphones separated by known distances can be used to locate a given source, which is known as acoustic localization. However, acoustic localization with infrasound is particularly challenging due to contamination from other signals, sensitivity to wind noise and producing a trusted source for system development. The objective of the current work is to create an infrasonic source using a propane torch wand or a subwoofer and locate the source using multiple infrasonic microphones. This presentation will present preliminary results from various microphone configurations used to locate the source.

Movement strategy and performance in a high-volume order picking workstation.

PubMed

Könemann, Reinier; Bosch, Tim; de Looze, Michiel

2012-01-01

The design of a work station generally prescribes a global movement pattern of the operator, but also leaving some degrees of freedom regarding movement strategy. For a specific order picking work station, we studied the movement strategies, the underlying factors and its impact on performance. Eight subjects performed a task comprising, the picking and placing of an object and pressing a button in eight conditions varying in product weight, movement direction (left vs. right), and placing distance. Movements were analyzed and cycle times were obtained from video-recordings. We observed various types of strategy regarding hand use and global placing mode (reaching vs. placing). The different strategies did not show clear relationships with performance (in contrast to the various work place factors). Ergonomically spoken, the fact that the workstation allows movement variation without loss of performance, is favorable.

Flexural properties of reinforced date palm fibres concrete in Sahara climate

NASA Astrophysics Data System (ADS)

Abani, S.; Kriker, A.; Khenfer, M. M.

2018-05-01

The mechanical characteristics of fibres reinforced concrete depend on many factors which are; the conditions of the work, the dosage, the distance between fibres and their orientation and distribution in the concrete. There are also other factors concerns the fibres themselves such as: the proportion of the length of the fibres to their diameter, their nature, the mechanical characteristics and the geometrical form. The main objective of our work is to contribute in the estimation of the vegetable fibres of the palm-trees that exist too much in our region and to introduce them scientifically in the domain of construction with taking into consideration the climatic conditions of the use. In this work, we will study the effect of the palm fibres on the mechanical characteristics of the concrete, such as: the strength of tensile by flexion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conn, A. R.; Parker, Q. A.; Zucker, D. B.

In 'A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude (Part I)', a new technique was introduced for obtaining distances using the tip of the red giant branch (TRGB) standard candle. Here we describe a useful complement to the technique with the potential to further reduce the uncertainty in our distance measurements by incorporating a matched-filter weighting scheme into the model likelihood calculations. In this scheme, stars are weighted according to their probability of being true object members. We then re-test our modified algorithm using random-realization artificial data to verify the validity of the generated posterior probability distributionsmore » (PPDs) and proceed to apply the algorithm to the satellite system of M31, culminating in a three-dimensional view of the system. Further to the distributions thus obtained, we apply a satellite-specific prior on the satellite distances to weight the resulting distance posterior distributions, based on the halo density profile. Thus in a single publication, using a single method, a comprehensive coverage of the distances to the companion galaxies of M31 is presented, encompassing the dwarf spheroidals Andromedas I-III, V, IX-XXVII, and XXX along with NGC 147, NGC 185, M33, and M31 itself. Of these, the distances to Andromedas XXIV-XXVII and Andromeda XXX have never before been derived using the TRGB. Object distances are determined from high-resolution tip magnitude posterior distributions generated using the Markov Chain Monte Carlo technique and associated sampling of these distributions to take into account uncertainties in foreground extinction and the absolute magnitude of the TRGB as well as photometric errors. The distance PPDs obtained for each object both with and without the aforementioned prior are made available to the reader in tabular form. The large object coverage takes advantage of the unprecedented size and photometric depth of the Pan-Andromeda Archaeological Survey. Finally, a preliminary investigation into the satellite density distribution within the halo is made using the obtained distance distributions. For simplicity, this investigation assumes a single power law for the density as a function of radius, with the slope of this power law examined for several subsets of the entire satellite sample.« less

The Spiral Arm Segments of the Galaxy within 3 kpc from the Sun: A Statistical Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griv, Evgeny; Jiang, Ing-Guey; Hou, Li-Gang, E-mail: griv@bgu.ac.il

As can be reasonably expected, upcoming large-scale APOGEE, GAIA, GALAH, LAMOST, and WEAVE stellar spectroscopic surveys will yield rather noisy Galactic distributions of stars. In view of the possibility of employing these surveys, our aim is to present a statistical method to extract information about the spiral structure of the Galaxy from currently available data, and to demonstrate the effectiveness of this method. The model differs from previous works studying how objects are distributed in space in its calculation of the statistical significance of the hypothesis that some of the objects are actually concentrated in a spiral. A statistical analysismore » of the distribution of cold dust clumps within molecular clouds, H ii regions, Cepheid stars, and open clusters in the nearby Galactic disk within 3 kpc from the Sun is carried out. As an application of the method, we obtain distances between the Sun and the centers of the neighboring Sagittarius arm segment, the Orion arm segment in which the Sun is located, and the Perseus arm segment. Pitch angles of the logarithmic spiral segments and their widths are also estimated. The hypothesis that the collected objects accidentally form spirals is refuted with almost 100% statistical confidence. We show that these four independent distributions of young objects lead to essentially the same results. We also demonstrate that our newly deduced values of the mean distances and pitch angles for the segments are not too far from those found recently by Reid et al. using VLBI-based trigonometric parallaxes of massive star-forming regions.« less

The Generation of the Distant Kuiper Belt by Planet Nine from an Initially Broad Perihelion Distribution

NASA Astrophysics Data System (ADS)

Khain, Tali; Batygin, Konstantin; Brown, Michael E.

2018-06-01

The observation that the orbits of long-period Kuiper Belt objects (KBOs) are anomalously clustered in physical space has recently prompted the Planet Nine hypothesis—the proposed existence of a distant and eccentric planetary member of our solar system. Within the framework of this model, a Neptune-like perturber sculpts the orbital distribution of distant KBOs through a complex interplay of resonant and secular effects, such that in addition to perihelion-circulating objects, the surviving orbits get organized into apsidally aligned and anti-aligned configurations with respect to Planet Nine’s orbit. In this work, we investigate the role of Kuiper Belt initial conditions on the evolution of the outer solar system using numerical simulations. Intriguingly, we find that the final perihelion distance distribution depends strongly on the primordial state of the system, and we demonstrate that a bimodal structure corresponding to the existence of both aligned and anti-aligned clusters is only reproduced if the initial perihelion distribution is assumed to extend well beyond ∼36 au. The bimodality in the final perihelion distance distribution is due to the existence of permanently stable objects, with the lower perihelion peak corresponding to the anti-aligned orbits and the higher perihelion peak corresponding to the aligned orbits. We identify the mechanisms that enable the persistent stability of these objects and locate the regions of phase space in which they reside. The obtained results contextualize the Planet Nine hypothesis within the broader narrative of solar system formation and offer further insight into the observational search for Planet Nine.

Symbolic objects as sediments of the intersubjective stream of feelings.

PubMed

Guimarães, Danilo Silva

2010-09-01

Taking into account that feeling is "the critical mediating process of the person-world relationships" (Josephs, Theory & Psychology 10(6):815, 2000), this article focuses on the artistic symbolic object as constraints that direct someone's feelings. Johansen (2010) states that the literary discourse "is designed to arousing and forming the feelings of listeners and readers" (p. 185). Distancing from strict literary production, I've used the testimony of the Brazilian songwriter, composer and performer, Tom Zé (2003), in order to discuss the intersubjective aspect of feelings articulation in his artistic work. Is proposed that the creative process of a symbolic object, which can be considered art, is a circumstance of a most general intersubjective-cultural process in which novel objects are built. If the specificity of art is to give a symbolic shape to human feeling (cf. Langer 1953), I argue that it is a sort of mediation which allows otherness to elaborate their affections through its objective guidance. In contrast with the scientific method of objective creation that is an effort for silencing contradictions (cf. Stengers 2002), the object of art remains open to multiple interpretations, stimulating the other to recursively speak and feel through it.

Study of Pressure Oscillations in Supersonic Parachute

NASA Astrophysics Data System (ADS)

Dahal, Nimesh; Fukiba, Katsuyoshi; Mizuta, Kazuki; Maru, Yusuke

2018-04-01

Supersonic parachutes are a critical element of planetary mission whose simple structure, light-weight characteristics together with high ratio of aerodynamic drag makes them the most suitable aerodynamic decelerators. The use of parachute in supersonic flow produces complex shock/shock and wake/shock interaction giving rise to dynamic pressure oscillations. The study of supersonic parachute is difficult, because parachute has very flexible structure which makes obtaining experimental pressure data difficult. In this study, a supersonic wind tunnel test using two rigid bodies is done. The wind tunnel test was done at Mach number 3 by varying the distance between the front and rear objects, and the distance of a bundle point which divides suspension lines and a riser. The analysis of Schlieren movies revealed shock wave oscillation which was repetitive and had large pressure variation. The pressure variation differed in each case of change in distance between the front and rear objects, and the change in distance between riser and the rear object. The causes of pressure oscillation are: interaction of wake caused by front object with the shock wave, fundamental harmonic vibration of suspension lines, interference between shock waves, and the boundary layer of suspension lines.

Evanescent-Wave Filtering in Images Using Remote Terahertz Structured Illumination

NASA Astrophysics Data System (ADS)

Flammini, M.; Pontecorvo, E.; Giliberti, V.; Rizza, C.; Ciattoni, A.; Ortolani, M.; DelRe, E.

2017-11-01

Imaging with structured illumination allows for the retrieval of subwavelength features of an object by conversion of evanescent waves into propagating waves. In conditions in which the object plane and the structured-illumination plane do not coincide, this conversion process is subject to progressive filtering of the components with high spatial frequency when the distance between the two planes increases, until the diffraction-limited lateral resolution is restored when the distance exceeds the extension of evanescent waves. We study the progressive filtering of evanescent waves by developing a remote super-resolution terahertz imaging system operating at a wavelength λ =1.00 mm , based on a freestanding knife edge and a reflective confocal terahertz microscope. In the images recorded with increasing knife-edge-to-object-plane distance, we observe the transition from a super-resolution of λ /17 ≃60 μ m to the diffraction-limited lateral resolution of Δ x ≃λ expected for our confocal microscope. The extreme nonparaxial conditions are analyzed in detail, exploiting the fact that, in the terahertz frequency range, the knife edge can be positioned at a variable subwavelength distance from the object plane. Electromagnetic simulations of radiation scattering by the knife edge reproduce the experimental super-resolution achieved.

Phase-slope and phase measurements of tunable CW-THz radiation with terahertz comb for wide-dynamic-range, high-resolution, distance measurement of optically rough object.

PubMed

Yasui, Takeshi; Fujio, Makoto; Yokoyama, Shuko; Araki, Tsutomu

2014-07-14

Phase measurement of continuous-wave terahertz (CW-THz) radiation is a potential tool for direct distance and imaging measurement of optically rough objects due to its high robustness to optical rough surfaces. However, the 2π phase ambiguity in the phase measurement of single-frequency CW-THz radiation limits the dynamic range of the measured distance to the order of the wavelength used. In this article, phase-slope measurement of tunable CW-THz radiation with a THz frequency comb was effectively used to extend the dynamic range up to 1.834 m while maintaining an error of a few tens µm in the distance measurement of an optically rough object. Furthermore, a combination of phase-slope measurement of tunable CW-THz radiation and phase measurement of single-frequency CW-THz radiation enhanced the distance error to a few µm within the dynamic range of 1.834 m without any influence from the 2π phase ambiguity. The proposed method will be a powerful tool for the construction and maintenance of large-scale structures covered with optically rough surfaces.

Near Work Related Parameters and Myopia in Chinese Children: the Anyang Childhood Eye Study

PubMed Central

Li, Shi-Ming; Li, Si-Yuan; Kang, Meng-Tian; Zhou, Yuehua; Liu, Luo-Ru; Li, He; Wang, Yi-Peng; Zhan, Si-Yan; Gopinath, Bamini; Mitchell, Paul; Wang, Ningli

2015-01-01

Purpose To examine the associations of near work related parameters with spherical equivalent refraction and axial length in Chinese children. Methods A total of 1770 grade 7 students with mean age of 12.7 years were examined with cycloplegic autorefraction and axial length. Questions were asked regarding time spent in near work and outdoors per day, and near work related parameters. Results Multivariate models revealed the following associations with greater odds of myopia: continuous reading (> 45min), odds ratio [OR], 1.4; 95% confidence interval [CI], 1.1-1.8; close television viewing distance (≤ 3m), OR, 1.7; 95% CI, 1.2-2.3; head tilt when writing, OR, 1.3; 95% CI, 1.1-1.7, and desk lighting using fluorescent vs. incandescent lamp, OR, 1.5; 95% CI, 1.2-2.0. These factors, together with close reading distance and close nib-to-fingertip distance were significantly associated with greater myopia (P<0.01). Among near work activities, only reading more books for pleasure was significantly associated with greater myopia (P=0.03). Television viewing distance (≤ 3 m), fluorescent desk light, close reading distance (≤20 cm) and close nib-to-fingertip distance (≤ 2 cm) were significantly associated with longer axial length (P<0.01). Reading distance, desk light, and reading books for pleasure had significant interaction effects with parental myopia. Conclusions Continuous reading, close distances of reading, television viewing and nib-to-fingertip, head tilt when writing, reading more books for pleasure and use of fluorescent desk light were significantly associated with myopia in 12-year-old Chinese children, which indicates that visual behaviors and environments may be important factors mediating the effects of near work on myopia. PMID:26244865

Administration of Distance-Teaching Institutions. A Manual.

ERIC Educational Resources Information Center

Dodds, Tony, Comp.

Guidance for distance teaching media selection, management, and program organization is offered in this two-part manual. Each of eight units includes questions to be addressed, behavioral objectives, comments, exercises, and assignments. The first unit, a general introduction to distance teaching, is followed by four units covering distance…

Adult Education at a Distance.

ERIC Educational Resources Information Center

Gaudet, Alphonse

This document, which examines the use of educational technologies for distance education for adults in Canada, consists of five narrative sections and a bibliography. The first section introduces the topic and the document's objectives (to describe those technologies used in Canadian adult distance education, paying particular attention to those…

30 CFR 285.543 - Example of how the inverse distance formula works.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Example of how the inverse distance formula works. 285.543 Section 285.543 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR... Financial Assurance Requirements Revenue Sharing with States § 285.543 Example of how the inverse distance...

Managing Complex Distance Education Projects in a Telework Environment

ERIC Educational Resources Information Center

Ally, Mohamed; Cleveland-Innes, Marti; Wiseman, Colin

2010-01-01

The advances of communication technologies have allowed professionals to work on distance education projects in a telework environment. Managers of these projects must have the skills to manage the projects from a distance. They must be able to select the appropriate team members to work on the project, orient team members, and monitor team…

The allocation of attention and working memory in visual crowding.

PubMed

Bacigalupo, Felix; Luck, Steven J

2015-06-01

When the distance between a visual target and nearby flankers falls below a critical distance, target discrimination declines precipitously. This is called "crowding." Many researchers have proposed that selective attention plays a role in crowding. However, although some research has examined the effects of directing attention toward versus away from the targets, no previous research has assessed how attentional allocation varies as a function of target-flanker distance in crowding. Here, we used ERPs to assess the operation of attention during crowding, focusing on the attention-related N2pc component. We used a typical crowding task in which participants were asked to report the category (vowel/consonant) of a lateralized target letter flanked by distractor letters at different distances. We tested the hypothesis that attention fails when the target-flanker distance becomes too small for attention to operate effectively. Consistent with this hypothesis, we found that N2pc amplitude was maximal at intermediate target-flanker distances and decreased substantially when crowding became severe. In addition, we examined the sustained posterior contralateral negativity (SPCN), which reflects the amount of information being maintained in working memory. Unlike the N2pc component, the SPCN increased in amplitude at small target-flanker distances, suggesting that observers stored information about the target and flankers in working memory when attention failed to select the target. Together, the N2pc and SPCN results suggest that attention and working memory play distinctive roles in crowding: Attention operates to minimize interference from the flankers at intermediate target-flanker distances, whereas working memory may be recruited when attention fails to select the target at small target-flanker distances.

New method for estimating low-earth-orbit collision probabilities

NASA Technical Reports Server (NTRS)

Vedder, John D.; Tabor, Jill L.

1991-01-01

An unconventional but general method is described for estimating the probability of collision between an earth-orbiting spacecraft and orbital debris. This method uses a Monte Caralo simulation of the orbital motion of the target spacecraft and each discrete debris object to generate an empirical set of distances, each distance representing the separation between the spacecraft and the nearest debris object at random times. Using concepts from the asymptotic theory of extreme order statistics, an analytical density function is fitted to this set of minimum distances. From this function, it is possible to generate realistic collision estimates for the spacecraft.

Profile fitting in crowded astronomical images

NASA Astrophysics Data System (ADS)

Manish, Raja

Around 18,000 known objects currently populate the near Earth space. These constitute active space assets as well as space debris objects. The tracking and cataloging of such objects relies on observations, most of which are ground based. Also, because of the great distance to the objects, only non-resolved object images can be obtained from the observations. Optical systems consist of telescope optics and a detector. Nowadays, usually CCD detectors are used. The information that is sought to be extracted from the frames are the individual object's astrometric position. In order to do so, the center of the object's image on the CCD frame has to be found. However, the observation frames that are read out of the detector are subject to noise. There are three different sources of noise: celestial background sources, the object signal itself and the sensor noise. The noise statistics are usually modeled as Gaussian or Poisson distributed or their combined distribution. In order to achieve a near real time processing, computationally fast and reliable methods for the so-called centroiding are desired; analytical methods are preferred over numerical ones of comparable accuracy. In this work, an analytic method for the centroiding is investigated and compared to numerical methods. Though the work focuses mainly on astronomical images, same principle could be applied on non-celestial images containing similar data. The method is based on minimizing weighted least squared (LS) error between observed data and the theoretical model of point sources in a novel yet simple way. Synthetic image frames have been simulated. The newly developed method is tested in both crowded and non-crowded fields where former needs additional image handling procedures to separate closely packed objects. Subsequent analysis on real celestial images corroborate the effectiveness of the approach.

Celebrating Distance Teaching Innovations: The Certificate in Distance Teaching.

ERIC Educational Resources Information Center

Boylan, Colin; Tuovinen, Juhani

Charles Sturt University (Riverina, Australia) has initiated the Certificate in Distance Teaching course for rural teachers working in a distance education setting to extend their understandings about rural and distance education topics. Two semester-long subjects constitute the course: pedagogy of distance teaching and organization of distance…

Evaluation of Image Segmentation and Object Recognition Algorithms for Image Parsing

DTIC Science & Technology

2013-09-01

generation of the features from the key points. OpenCV uses Euclidean distance to match the key points and has the option to use Manhattan distance...feature vector includes polarity and intensity information. Final step is matching the key points. In OpenCV , Euclidean distance or Manhattan...the code below is one way and OpenCV offers the function radiusMatch (a pair must have a distance less than a given maximum distance). OpenCV’s

Acculturative Family Distancing (AFD) and Depression in Chinese American Families

ERIC Educational Resources Information Center

Hwang, Wei-Chin; Wood, Jeffrey J.; Fujimoto, Ken

2010-01-01

Objective: Knowledge of acculturative processes and their impact on immigrant families remains quite limited. Acculturative family distancing (AFD) is the distancing that occurs between immigrant parents and their children and is caused by breakdowns in communication and cultural value differences. It is a more proximal and problem-focused…

Effects of overhead work involving different heights and distances on neck and shoulder muscle activity.

PubMed

Shin, Seung-Je; Yoo, Won-Gyu

2015-06-05

Although overhead work is closely related to musculoskeletal disorders, it is difficult to avoid these postures in daily working conditions. In industrial tasks that require elevated arm postures above shoulder height, flexibility in the location of the task is necessary. This study investigated the sternocleidomastoid, upper trapezius, lower trapezius, and anterior deltoid, serratus anterior muscle activities during overhead work involving four different height and distance locations performed by healthy adult participants. Eighteen young male right-hand-dominant workers were recruited. The right upper trapezius, lower trapezius, serratus anterior, anterior deltoid, and sternocleidomastoid muscle activities were measured under for overhead work condition (Location 1: overhead work with a height of 10 cm above the head of each subject and distance of 15 cm, Location 2: overhead work with a height of 10 cm above the head of each subject and distance of 30 cm, Location 3: overhead work with a height of 20 cm above the head of each subject and distance of 15 cm, Location 4: overhead work with a height of 20 cm above the head of each subject and distance of 30 cm). In Location 3, there was significantly higher neck extension range of motion compared to Location 1, Location 2 and Location 4. In Location 1, the activities of the upper trapezius, lower trapezius, serratus anterior, anterior deltoid, and sternocleidomastoid muscles were significantly lower than those in Location 3 (p<0.05). In Location 2, the activities of the upper trapezius, lower trapezius, serratus anterior, anterior deltoid, and sternocleidomastoid muscles were significantly lower than those in Location 4 (p<0.05). In Location 1, there were significantly lower upper trapezius, lower trapezius, serratus anterior, and anterior deltoid muscle activities than in Location 2 (p<0.05). In Location 3, there were significantly lower upper trapezius, lower trapezius, serratus anterior, and anterior deltoid muscle activities than in Location 4 (p<0.05). In Location 1, there was significantly higher sternocleidomastoid muscle activity than in Location 2 (p<0.05). Finally, In Location 3, there was significantly higher sternocleidomastoid muscle activity than in Location 4 (p<0.05). Overhead workers should engage in work that involves a low height and near distance. Height appears to be a stronger risk factor than distance in overhead work.

Method for targetless tracking subpixel in-plane movements.

PubMed

Espinosa, Julian; Perez, Jorge; Ferrer, Belen; Mas, David

2015-09-01

We present a targetless motion tracking method for detecting planar movements with subpixel accuracy. This method is based on the computation and tracking of the intersection of two nonparallel straight-line segments in the image of a moving object in a scene. The method is simple and easy to implement because no complex structures have to be detected. It has been tested and validated using a lab experiment consisting of a vibrating object that was recorded with a high-speed camera working at 1000 fps. We managed to track displacements with an accuracy of hundredths of pixel or even of thousandths of pixel in the case of tracking harmonic vibrations. The method is widely applicable because it can be used for distance measuring amplitude and frequency of vibrations with a vision system.

Characterizing Water Ice Clouds on the Coldest Known Brown Dwarf

NASA Astrophysics Data System (ADS)

Luhman, Kevin; Burgasser, Adam; Cushing, Michael; Esplin, Taran; Fortney, Jonathan; Hardegree-Ullman, Kevin; Marley, Mark; Morley, Caroline; Schneider, Adam; Trucks, Jesica

2014-12-01

We have conducted a search for high proper motion brown dwarfs using multi-epoch all-sky mid-infrared images from the WISE satellite. Through this work, we have discovered an object with a parallactic distance of 2.3 pc and a temperature of 250 K, making it the 4th closest neighbor of the Sun, and the coldest known brown dwarf. Because of its extreme proximity and temperature, it represents an unparalleled laboratory for studying planet-like atmospheres in an unexplored temperature regime. We propose to photometrically monitor this object with IRAC to 1) detect and characterize water ice clouds in its atmosphere via the short-term variations induced during rotation and 2) constrain the long-term evolution of its clouds across a period of months.

Analysis of thick brain sections by obverse-reverse computer microscopy: application of a new, high clarity Golgi-Nissl stain.

PubMed

Glaser, E M; Van der Loos, H

1981-08-01

Exceptionally clear Golgi-Nissl sections of 300 micron thickness have been morphometrically studied by light microscopy using oil immersion objectives. The clarity results from a new variation of a staining procedure that combines Golgi and Nissl images in one section. A viewing technique has been developed that permits a histologic preparation to be examined from its obverse (or normally viewed) side and its reverse (or under) side. The technique was designed for use with a computer microscope but can be employed with any light microscope whose stage position can be measured within 100 micron. Sections thicker than 300 micron can be studied dependent on the working distance of the objective lens, provided that the clarity of the material permits it.

Distance Education and Open Learning in Sub-Saharan Africa: Criteria and Conditions for Quality and Critical Success Factor-- Working Group on Distance Education and Open Learning. A Survey of Policy and Practice. Final Report

ERIC Educational Resources Information Center

Commonwealth of Learning, 2004

2004-01-01

Both of these "Surveys of policy and practice" were conducted on behalf of COL by the South African Institute for Distance Education (SAIDE) as part of COL's partnership agreement with the Association for the Development of Education in Africa (ADEA) Working Group on Distance Education and Open Learning. The first report identifies…

Preparation of wholemount mouse intestine for high-resolution three-dimensional imaging using two-photon microscopy.

PubMed

Appleton, P L; Quyn, A J; Swift, S; Näthke, I

2009-05-01

Visualizing overall tissue architecture in three dimensions is fundamental for validating and integrating biochemical, cell biological and visual data from less complex systems such as cultured cells. Here, we describe a method to generate high-resolution three-dimensional image data of intact mouse gut tissue. Regions of highest interest lie between 50 and 200 mum within this tissue. The quality and usefulness of three-dimensional image data of tissue with such depth is limited owing to problems associated with scattered light, photobleaching and spherical aberration. Furthermore, the highest-quality oil-immersion lenses are designed to work at a maximum distance of

Prior Work and Educational Experience Are Not Associated With Successful Completion of a Master's-Level, Distance Education Midwifery Program.

PubMed

Niemczyk, Nancy A; Cutts, Alison; Perlman, Dana B

2018-03-01

In order to increase and diversify the midwifery workforce, admissions criteria for midwifery education programs must not contain unnecessary barriers to entry. Once accepted, students need to successfully complete the program. Many admissions criteria commonly used in midwifery education programs in the United States are not evidence based and could be unnecessary barriers to education. The primary objective of this study was to identify factors known during the admission process that were related to successful completion or failure to complete a midwifery program educating both student nurse-midwives (SNMs) and student midwives (SMs); a secondary objective was to quantify reasons for program noncompletion. This master's-level, distance education program educates a diverse group of both SNMs and SMs. A pilot, retrospective cohort study examined all students matriculating at the program from fall 2012 on and scheduled to graduate by summer 2016 (N = 58). Demographic information, admissions information, academic records, and advising notes were reviewed. Reasons for noncompletion were identified, and characteristics were compared between students who did and did not complete the program. Program completion was not significantly associated with students' status as nurses prior to admission, labor and delivery nursing experience, length of nursing experience, nursing degree held, presence of children at home, working while in school, or undergraduate grade point average. Being a nurse, years of nursing experience, type of nursing degree, or labor and delivery nursing experience were not associated with completion of this midwifery program. © 2018 by the American College of Nurse-Midwives.

Implementing Constructivist Approach into Online Course Designs in Distance Education Institute at Eastern Mediterranean University

ERIC Educational Resources Information Center

Gazi, Zehra A.

2009-01-01

Change and development in work settings for better working practice through projects has become essential. And, in this context, learning through working practice is constructed by participatory action research. This work-based research has a significant role to contribute innovative practice of Distance Education Institute at Eastern…

Travel patterns during pregnancy: comparison between Global Positioning System (GPS) tracking and questionnaire data

PubMed Central

2013-01-01

Background Maternal exposures to traffic-related air pollution have been associated with adverse pregnancy outcomes. Exposures to traffic-related air pollutants are strongly influenced by time spent near traffic. However, little is known about women’s travel activities during pregnancy and whether questionnaire-based data can provide reliable information on travel patterns during pregnancy. Objectives Examine women’s in-vehicle travel behavior during pregnancy and examine the difference in travel data collected by questionnaire and global positioning system (GPS) and their potential for exposure error. Methods We measured work-related travel patterns in 56 pregnant women using a questionnaire and one-week GPS tracking three times during pregnancy (<20 weeks, 20–30 weeks, and >30 weeks of gestation). We compared self-reported activities with GPS-derived trip distance and duration, and examined potentially influential factors that may contribute to differences. We also described in-vehicle travel behavior by pregnancy periods and influences of demographic and personal factors on daily travel times. Finally, we estimated personal exposure to particle-bound polycyclic aromatic hydrocarbon (PB-PAH) and examined the magnitude of exposure misclassification using self-reported vs. GPS travel data. Results Subjects overestimated both trip duration and trip distance compared to the GPS data. We observed moderately high correlations between self-reported and GPS-recorded travel distance (home to work trips: r = 0.88; work to home trips: r = 0.80). Better agreement was observed between the GPS and the self-reported travel time for home to work trips (r = 0.77) than work to home trips (r = 0.64). The subjects on average spent 69 and 93 minutes traveling in vehicles daily based on the GPS and self-reported data, respectively. Longer daily travel time was observed among participants in early pregnancy, and during certain pregnancy periods in women with higher education attainment, higher income, and no children. When comparing self-reported vs. GPS data, we found that estimated personal exposure to PB-PAH did not differ remarkably at the population level, but the difference was large at an individual level. Conclusion Self-reported home-to-work data overestimated both trip duration and trip distance compared to GPS data. Significant differences in PAH exposure estimates were observed at individual level using self-reported vs. GPS data, which has important implications in air pollution epidemiological studies. PMID:24107241

Super-Earth at a distance of less than 1,000 AU in solar system is absent

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.

2017-12-01

Numerous observations have shown that the Kuiper belt is a dynamically stable system. The source of cometary nuclei can be a scattered disk. It is an area created by outward-directed gravitational perturbations of the outer giant planets more than 4 billion years ago. The objects of the scattered disk are similar to the bodies of the Kuiper belt. But they go in their orbits for distances up to several hundred astronomical units (AU). In 2016 Brown and Batygin reported about indirect evidence of the existence of so far unknown ninth planet in the Solar system. They suggested, that orbits of 6 known trans-Neptunian objects of scattered disk are oriented so, that they can be influenced by a large, yet unknown body. We draw attention to the fact, that these 6 objects in close to their discovering moments were located at perihelion. We assume that for many orders of magnitude a larger number of the same trans-Neptunian objects should be located at a greater distance from the perihelion. Therefore, a possible number of the same trans-Neptunian objects should be counted in many thousands. We used the observation data obtained by Space Telescope "WISE" (Wide-Field Infrared Survey Explorer). It was established that there is no analogue of the giant planet Saturn at distances up to 30000 AU. This circumstance allowed us to calculate that at distances up to 1000 AU it would be clearly visible planetary body with a radius of more than 11000 km. That is, a planet with a possible mass of about 10 Earth masses and an "earth" density (5.52 t/m3). If we take into account that the density of the "average" trans-Neptunian object differs little from 2 t/m3, the radius of such a body will increase to 19200 km. And then the limit of detection of the body will increase by almost 4 times: up to 4000 AU. (!) Thus, either unknown 9th planet is now even further, or our results cannot be directly scaled for the planet "Super-Earth", which at such large distance can have a disproportionately low source of internal heat.

Electric fish as natural models for technical sensor systems

NASA Astrophysics Data System (ADS)

von der Emde, Gerhard; Bousack, Herbert; Huck, Christina; Mayekar, Kavita; Pabst, Michael; Zhang, Yi

2009-05-01

Instead of vision, many animals use alternative senses for object detection. Weakly electric fish employ "active electrolocation", during which they discharge an electric organ emitting electrical current pulses (electric organ discharges, EOD). Local EODs are sensed by electroreceptors in the fish's skin, which respond to changes of the signal caused by nearby objects. Fish can gain information about attributes of an object, such as size, shape, distance, and complex impedance. When close to the fish, each object projects an 'electric image' onto the fish's skin. In order to get information about an object, the fish has to analyze the object's electric image by sampling its voltage distribution with the electroreceptors. We now know a great deal about the mechanisms the fish use to gain information about objects in their environment. Inspired by the remarkable capabilities of weakly electric fish in detecting and recognizing objects with their electric sense, we are designing technical sensor systems that can solve similar sensing problems. We applied the principles of active electrolocation to devices that produce electrical current pulses in water and simultaneously sense local current densities. Depending on the specific task, sensors can be designed which detect an object, localize it in space, determine its distance, and measure certain object properties such as material properties, thickness, or material faults. We present first experiments and FEM simulations on the optimal sensor arrangement regarding the sensor requirements e. g. localization of objects or distance measurements. Different methods of the sensor read-out and signal processing are compared.

Developing Identities in the Workplace: Students' Experiences of Distance Early Childhood Teacher Education

ERIC Educational Resources Information Center

Tate, Alice

2016-01-01

In Aotearoa New Zealand, many early childhood teachers gain their teaching qualification via distance study while working in an early childhood centre. Early childhood teachers work in a team environment, and it is important to understand more about how distance students negotiate changes in their workplace practice as their professional knowledge…

Science Practical Work Instructional Technologies and Open Distance Learning in Science Teacher Training: A Case Study in Zimbabwe

ERIC Educational Resources Information Center

Bhukuvhani, Crispen; Mupa, Mathew; Mhishi, Misheck; Dziva, Daimond

2012-01-01

The practical work component offers unique challenges for university science courses. This is even more pertinent in an Open and Distance Learning (ODL) environment like the Bindura University of Science Education's Virtual and Open Distance Learning (VODL) programme. Effective ODL education should be flexible enough to accommodate science…

Secular Extragalactic Parallax and Geometric Distances with Gaia Proper Motions

NASA Astrophysics Data System (ADS)

Paine, Jennie; Darling, Jeremiah K.

2018-06-01

The motion of the Solar System with respect to the cosmic microwave background (CMB) rest frame creates a well measured dipole in the CMB, which corresponds to a linear solar velocity of about 78 AU/yr. This motion causes relatively nearby extragalactic objects to appear to move compared to more distant objects, an effect that can be measured in the proper motions of nearby galaxies. An object at 1 Mpc and perpendicular to the CMB apex will exhibit a secular parallax, observed as a proper motion, of 78 µas/yr. The relatively large peculiar motions of galaxies make the detection of secular parallax challenging for individual objects. Instead, a statistical parallax measurement can be made for a sample of objects with proper motions, where the global parallax signal is modeled as an E-mode dipole that diminishes linearly with distance. We present preliminary results of applying this model to a sample of nearby galaxies with Gaia proper motions to detect the statistical secular parallax signal. The statistical measurement can be used to calibrate the canonical cosmological “distance ladder.”

Near-Earth Objects. Chapter 27

NASA Technical Reports Server (NTRS)

Harris, Alan W.; Drube, Line; McFadden, Lucy A.; Binzel, Richard P.

2014-01-01

A near-Earth object (NEO) is an asteroid or comet orbiting the Sun with a perihelion distance of less than 1.3 Astronomical Units (AU) (1 AU, an astronomical unit, is the mean distance between the Earth and the Sun, around 150 million kilometers). If the orbit of an NEO can bring it to within 0.05 AU of the Earth's orbit, and it is larger than about 120 meters, it is termed a potentially hazardous object (PHO); an object of this size is likely to survive passage through the atmosphere and cause extensive damage on impact. (The acronyms NEA and PHO are used when referring specifically to asteroids.)

Height perception influenced by texture gradient.

PubMed

Tozawa, Junko

2012-01-01

Three experiments were carried out to examine whether a texture gradient influences perception of relative object height. Previous research implicated texture cues in judgments of object width, but similar influences have not been demonstrated for relative height. In this study, I evaluate a hypothesis that the projective ratio of the number of texture elements covered by the objects combined with the ratio of the retinal object heights determines percepts of relative object height. Density of texture background was varied: four density conditions ranged from no-texture to very dense texture. In experiments 1 and 2, participants judged the height of comparison bar compared to the standard bar positioned on no-texture or textured backgrounds. Results showed relative height judgments differed with texture manipulations, consistent with predictions from a hypothesised combination of the number of texture elements with retinal height (experiment 1), or partially consistent with this hypothesis (experiment 2). In experiment 2, variations in the position of a comparison object showed that comparisons located far from the horizon were judged more poorly than in other positions. In experiment 3 I examined distance perception; relative distance judgments were found to be also affected by textured backgrounds. Results are discussed in terms of Gibson's relational theory and distance calibration theory.

New platform for evaluating ultrasound-guided interventional technologies

NASA Astrophysics Data System (ADS)

Kim, Younsu; Guo, Xiaoyu; Boctor, Emad M.

2016-04-01

Ultrasound-guided needle tracking systems are frequently used in surgical procedures. Various needle tracking technologies have been developed using ultrasound, electromagnetic sensors, and optical sensors. To evaluate these new needle tracking technologies, 3D volume information is often acquired to compute the actual distance from the needle tip to the target object. The image-guidance conditions for comparison are often inconsistent due to the ultrasound beam-thickness. Since 3D volumes are necessary, there is often some time delay between the surgical procedure and the evaluation. These evaluation methods will generally only measure the final needle location because they interrupt the surgical procedure. The main contribution of this work is a new platform for evaluating needle tracking systems in real-time, resolving the problems stated above. We developed new tools to evaluate the precise distance between the needle tip and the target object. A PZT element transmitting unit is designed as needle introducer shape so that it can be inserted in the needle. We have collected time of flight and amplitude information in real-time. We propose two systems to collect ultrasound signals. We demonstrate this platform on an ultrasound DAQ system and a cost-effective FPGA board. The results of a chicken breast experiment show the feasibility of tracking a time series of needle tip distances. We performed validation experiments with a plastisol phantom and have shown that the preliminary data fits a linear regression model with a RMSE of less than 0.6mm. Our platform can be applied to more general needle tracking methods using other forms of guidance.

Brown dwarf distances and atmospheres: Spitzer Parallaxes and the Keck/NIRSPEC upgrade

NASA Astrophysics Data System (ADS)

Martin, Emily C.

2018-01-01

Advances in infrared technology have been essential towards improving our understanding of the solar neighborhood, revealing a large population of brown dwarfs, which span the mass regime between planets and stars. My thesis combines near-infrared (NIR) spectroscopic and astrometric analysis of nearby low-mass stars and brown dwarfs with instrumentation work to upgrade the NIRSPEC instrument for the Keck II Telescope. I will present results from a program using Spitzer/IRAC data to measure precise locations and distances to 22 of the coldest and closest brown dwarfs. These distances allow us to constrain absolute physical properties, such as mass, radius, and age, of free-floating planetary-mass objects through comparison to atmospheric and evolutionary models. NIR spectroscopy combined with the Spitzer photometry reveals a detailed look into the atmospheres of brown dwarfs and gaseous extrasolar planets. Additionally, I will discuss the improvements we are making to the NIRSPEC instrument at Keck. NIRSPEC is a NIR echelle spectrograph, capable of R~2000 and R~25,000 observations in the 1-5 μm range. As part of the upgrade, I performed detector characterization, optical design of a new slit-viewing camera, mechanical testing, and electronics design. NIRSPEC’s increased efficiency will allow us to obtain moderate- and high-resolution NIR spectra of objects up to a magnitude fainter than the current NIRSPEC design. Finally, I will demonstrate the utility of a NIR laser frequency comb as a high-resolution calibrator. This new technology will revolutionize precision radial velocity measurements in the coming decade.

Movement of the projected pedicles relative to the projected vertebral body in a fourth lumbar vertebra during axial rotation.

PubMed

Coleman, Roger R; Thomas, I Walker

2004-01-01

One use of the anteroposterior lumbar radiograph is to determine axial (y-axis) rotation of the lumbar vertebrae. Rotation might be an element of interest to clinicians seeking to evaluate vertebral positioning. Correlate and quantify movements of the projected pedicles relative to the projected vertebral body during axial rotation and determine if vertebral asymmetry and changes in object film distance affect these movements. A three-dimensional computer model of the fourth and fifth lumbar vertebrae, a modeled radiograph source, and a modeled film were produced. The vertebral model was placed in various degrees of axial rotation at a number of different object film distances. Lines from the source were passed through the pedicles of the fourth lumbar vertebral model and additional lines erected tangent to the lateral body margins. These lines were extended to points of contact with the modeled film. The projected pedicles move relative to the projected vertebral body during y-axis rotation. Vertebral asymmetry and object film distances can also affect the distance of the projected pedicle relative to the projected lateral body margin. Axial rotation produces movement of the projected pedicles relative to the projected vertebral body. However, vertebral asymmetry and changes in object film distance also affect the position of the projected pedicles relative to the projected lateral body margin and might serve as confounders to the clinician seeking to analyze vertebral rotation through the use of the projected pedicles.

A method to quickly test the emissivity with an infrared thermal imaging system within a small distance

NASA Astrophysics Data System (ADS)

Wang, Xuan-yu; Hu, Rui; Wang, Rui-xin

2015-10-01

A simple method has been set up to quickly test the emissivity with an infrared thermal imaging system within a small distance according to the theory of measuring temperature by infrared system, which is based on the Planck radiation law and Lambert-beer law. The object's temperature is promoted and held on by a heater while a temperature difference has been formed between the target and environment. The emissivity of human skin, galvanized iron plate, black rubber and liquid water has been tested under the condition that the emissivity is set in 1.0 and the testing distance is 1m. According to the invariance of human's body temperature, a testing curve is established to describe that the thermal imaging temperatures various with the emissivity which is set in from 0.9 to 1.0. As a result, the method has been verified. The testing results show that the emissivity of human skin is 0.95. The emissivity of galvanized iron plate, black rubber and liquid water decreases with the increase of object's temperature. The emissivity of galvanized iron plate is far smaller than the one of human skin, black rubber or water. The emissivity of water slowly linearly decreases with the increase of its temperature. By the study, within a small distance and clean atmosphere, the infrared emissivity of objects may be expediently tested with an infrared thermal imaging system according to the method, which is promoting the object's temperature to make it different from the environment temperature, then simultaneously measures the environmental temperature, the real temperature and thermal imaging temperature of the object when the emissivity is set in 1.0 and the testing distance is 1.0m.

Improved Object Localization Using Accurate Distance Estimation in Wireless Multimedia Sensor Networks

PubMed Central

Ur Rehman, Yasar Abbas; Tariq, Muhammad; Khan, Omar Usman

2015-01-01

Object localization plays a key role in many popular applications of Wireless Multimedia Sensor Networks (WMSN) and as a result, it has acquired a significant status for the research community. A significant body of research performs this task without considering node orientation, object geometry and environmental variations. As a result, the localized object does not reflect the real world scenarios. In this paper, a novel object localization scheme for WMSN has been proposed that utilizes range free localization, computer vision, and principle component analysis based algorithms. The proposed approach provides the best possible approximation of distance between a wmsn sink and an object, and the orientation of the object using image based information. Simulation results report 99% efficiency and an error ratio of 0.01 (around 1 ft) when compared to other popular techniques. PMID:26528919

Kinematic measurement from panned cinematography.

PubMed

Gervais, P; Bedingfield, E W; Wronko, C; Kollias, I; Marchiori, G; Kuntz, J; Way, N; Kuiper, D

1989-06-01

Traditional 2-D cinematography has used a stationary camera with its optical axis perpendicular to the plane of motion. This method has constrained the size of the object plane or has introduced potential errors from a small subject image size with large object field widths. The purpose of this study was to assess a panning technique that could overcome the inherent limitations of small object field widths, small object image sizes and limited movement samples. The proposed technique used a series of reference targets in the object field that provided the necessary scales and origin translations. A 102 m object field was panned. Comparisons between criterion distances and film measured distances for field widths of 46 m and 22 m resulted in absolute mean differences that were comparable to that of the traditional method.

6-DoF Haptic Rendering Using Continuous Collision Detection between Points and Signed Distance Fields.

PubMed

Hongyi Xu; Barbic, Jernej

2017-01-01

We present an algorithm for fast continuous collision detection between points and signed distance fields, and demonstrate how to robustly use it for 6-DoF haptic rendering of contact between objects with complex geometry. Continuous collision detection is often needed in computer animation, haptics, and virtual reality applications, but has so far only been investigated for polygon (triangular) geometry representations. We demonstrate how to robustly and continuously detect intersections between points and level sets of the signed distance field. We suggest using an octree subdivision of the distance field for fast traversal of distance field cells. We also give a method to resolve continuous collisions between point clouds organized into a tree hierarchy and a signed distance field, enabling rendering of contact between rigid objects with complex geometry. We investigate and compare two 6-DoF haptic rendering methods now applicable to point-versus-distance field contact for the first time: continuous integration of penalty forces, and a constraint-based method. An experimental comparison to discrete collision detection demonstrates that the continuous method is more robust and can correctly resolve collisions even under high velocities and during complex contact.

Distance measurement based on light field geometry and ray tracing.

PubMed

Chen, Yanqin; Jin, Xin; Dai, Qionghai

2017-01-09

In this paper, we propose a geometric optical model to measure the distances of object planes in a light field image. The proposed geometric optical model is composed of two sub-models based on ray tracing: object space model and image space model. The two theoretic sub-models are derived on account of on-axis point light sources. In object space model, light rays propagate into the main lens and refract inside it following the refraction theorem. In image space model, light rays exit from emission positions on the main lens and subsequently impinge on the image sensor with different imaging diameters. The relationships between imaging diameters of objects and their corresponding emission positions on the main lens are investigated through utilizing refocusing and similar triangle principle. By combining the two sub-models together and tracing light rays back to the object space, the relationships between objects' imaging diameters and corresponding distances of object planes are figured out. The performance of the proposed geometric optical model is compared with existing approaches using different configurations of hand-held plenoptic 1.0 cameras and real experiments are conducted using a preliminary imaging system. Results demonstrate that the proposed model can outperform existing approaches in terms of accuracy and exhibits good performance at general imaging range.

2D and 3D X-ray phase retrieval of multi-material objects using a single defocus distance.

PubMed

Beltran, M A; Paganin, D M; Uesugi, K; Kitchen, M J

2010-03-29

A method of tomographic phase retrieval is developed for multi-material objects whose components each has a distinct complex refractive index. The phase-retrieval algorithm, based on the Transport-of-Intensity equation, utilizes propagation-based X-ray phase contrast images acquired at a single defocus distance for each tomographic projection. The method requires a priori knowledge of the complex refractive index for each material present in the sample, together with the total projected thickness of the object at each orientation. The requirement of only a single defocus distance per projection simplifies the experimental setup and imposes no additional dose compared to conventional tomography. The algorithm was implemented using phase contrast data acquired at the SPring-8 Synchrotron facility in Japan. The three-dimensional (3D) complex refractive index distribution of a multi-material test object was quantitatively reconstructed using a single X-ray phase-contrast image per projection. The technique is robust in the presence of noise, compared to conventional absorption based tomography.

Role of a texture gradient in the perception of relative size.

PubMed

Tozawa, Junko

2010-01-01

Two theories regarding the role of a texture gradient in the perception of the relative size of objects are compared. Relational theory states that relative size is directly specified by the projective ratio of the numbers of texture elements spanned by objects. Distance calibration theory assumes that relative size is a product of visual angle and distance, once the distance is specified by the texture. Experiment 1 involved three variables: background (no texture, texture gradient patterns), the ratio of heights of the comparison stimulus to a standard (three levels), and angular vertical separation of the standard stimulus below the horizon (two levels). The effect of the retinal length of the comparison stimulus was examined in experiment 2. In both experiments, participants judged both the apparent size and distance of a comparison stimulus relative to a standard stimulus. Results suggest that the cues selected by observers to judge relative size were to some degree different from those used to judge relative distance. Relative size was strongly affected by a texture gradient and the retinal length of a comparison stimulus whereas relative distance perception was affected by relative height. When dominant cues that specify size are different from those which specify distance, relational theory might provide a better account of relative size perception than distance calibration theory.

On the Distance Measurements toward Young Milky Way Objects. I. Study of IC 2944

NASA Astrophysics Data System (ADS)

Krełowski, J.; Strobel, A.; Godunova, V.; Bondar, A.

2017-12-01

We compare distances to a very young stellar aggregate, IC 2944, using three methods: direct parallaxes of Gaia, spectrophotometric parallax and our method based on intensities of interstellar CaII lines. The discrepancies between spectrophotometric distances and those, based on CaII K and H lines, were already reported. The interstellar CaII H and K lines allow one to determine both distances and radial velocities of the intervening clouds. Thus, these data allow us to check the aggregate membership. It is also possible to check the spectral classification of considered targets which is necessary for spectrophotometric parallaxes. Using three methods, we determined distances to IC 2944 stars. We demonstrate that CaII based distances agree very well with the kinematic ones but are generally much smaller than the spectrophotometric ones. We conclude that the majority of IC 2944 objects is obscured by clouds producing neutral ("gray") extinction which diminishes their brightness exactly like extended distances. This influences spectrophotometric parallaxes while those, based on the CaII lines, do not depend on extinction and this method seems to be the most reliable one inside the thin disk of our Galaxy. The Gaia trigonometric parallaxes lead to distances similar to those obtained using the CaII method if their errors are reasonably small.

Design of polarized infrared athermal telephoto objective for penetrating the fog

NASA Astrophysics Data System (ADS)

Gao, Duorui; Fu, Qiang; Zhao, Zhao; Zhao, Bin; Zhong, Lijun; Zhan, Juntong

2014-11-01

Polarized infrared imaging technology is a new detection technique which own the ability of spying through the fog, highlighting the target and recognizing the forgeries, these characters make it a good advantage of increasing the work distance in the fog. Compared to the traditional infrared imaging method, polarized infrared imaging can identify the background and target easily, that is the most distinguishing feature of polarized infrared imaging technology. Owning to the large refractive index of the infrared material, temperature change will bring defocus seriously, athermal infrared objective is necessarily. On the other hand, athermal objective has large total length, and hard to be integrated for their huge volume. However telephoto objective has the character of small volume and short total length. The paper introduce a method of polarized and athermal infrared telephoto objective which can spy the fog. First assign the optical power of the fore group and the rear group on the basis of the principle of telephoto objective, the power of the fore group is positive and the rear group is negative; then distribute the optical power within each group to realize the ability of athermalization, finally computer-aided software is used to correct aberration. In order to prove the feasibility of the scheme, an athermal optical system was designed by virtue of ZEMAX software which works at 8~12 µm, the focal length of 150mm, F number is 2, and total length of the telephoto objective is 120mm. The environment temperature analysis shows that the optical system have stable imaging quality, MTF is close to diffraction limit. This telephoto objective is available for infrared polarized imaging.

Spatial filtering velocimetry of objective speckles for measuring out-of-plane motion.

PubMed

Jakobsen, M L; Yura, H T; Hanson, S G

2012-03-20

This paper analyzes the dynamics of objective laser speckles as the distance between the object and the observation plane continuously changes. With the purpose of applying optical spatial filtering velocimetry to the speckle dynamics, in order to measure out-of-plane motion in real time, a rotational symmetric spatial filter is designed. The spatial filter converts the speckle dynamics into a photocurrent with a quasi-sinusoidal response to the out-of-plane motion. The spatial filter is here emulated with a CCD camera, and is tested on speckles arising from a real application. The analysis discusses the selectivity of the spatial filter, the nonlinear response between speckle motion and observation distance, and the influence of the distance-dependent speckle size. Experiments with the emulated filters illustrate performance and potential applications of the technology. © 2012 Optical Society of America

Optimal Superpositioning of Flexible Molecule Ensembles

PubMed Central

Gapsys, Vytautas; de Groot, Bert L.

2013-01-01

Analysis of the internal dynamics of a biological molecule requires the successful removal of overall translation and rotation. Particularly for flexible or intrinsically disordered peptides, this is a challenging task due to the absence of a well-defined reference structure that could be used for superpositioning. In this work, we started the analysis with a widely known formulation of an objective for the problem of superimposing a set of multiple molecules as variance minimization over an ensemble. A negative effect of this superpositioning method is the introduction of ambiguous rotations, where different rotation matrices may be applied to structurally similar molecules. We developed two algorithms to resolve the suboptimal rotations. The first approach minimizes the variance together with the distance of a structure to a preceding molecule in the ensemble. The second algorithm seeks for minimal variance together with the distance to the nearest neighbors of each structure. The newly developed methods were applied to molecular-dynamics trajectories and normal-mode ensembles of the Aβ peptide, RS peptide, and lysozyme. These new (to our knowledge) superpositioning methods combine the benefits of variance and distance between nearest-neighbor(s) minimization, providing a solution for the analysis of intrinsic motions of flexible molecules and resolving ambiguous rotations. PMID:23332072

Creation of Medicinal Chemistry Learning Communities Through Enhanced Technology and Interdisciplinary Collaboration

PubMed Central

Roche, Victoria

2012-01-01

Objectives. To build an integrated medicinal chemistry learning community of campus and distance pharmacy students though the use of innovative technology and interdisciplinary teaching. Design. Mechanisms were implemented to bring distance students into campus-based medicinal chemistry classrooms in real time, stimulate interaction between instructors and various student cohorts, and promote group work during class. Also, pharmacy clinician colleagues were recruited to contribute to the teaching of the 3 medicinal chemistry courses. Assessment. Student perceptions on the value of technology to build community and advance learning were gleaned from course evaluations, in class feedback, and conversations with class officers and student groups. Responses on a survey of second-year students confirmed the benefits of interdisciplinary content integration on engagement and awareness of the connection between drug chemistry and pharmacy practice. A survey of clinician colleagues who contributed to teaching the 3 medicinal chemistry courses found their views were similar to those of students. Conclusions. The purposeful use of technology united learners, fostered communication, and advanced content comprehension in 3 medicinal chemistry courses taught to campus and distance students. Teaching collaboration with pharmacy clinicians enhanced learner interest in course content and provided insight into the integrated nature of the profession of pharmacy. PMID:23129857

Rabies outbreak in Greece during 2012-2014: use of Geographical Information System for analysis, risk assessment and control.

PubMed

Giannakopoulos, A; Valiakos, G; Papaspyropoulos, K; Dougas, G; Korou, L M; Tasioudi, K E; Fthenakis, G C; Hutchings, M R; Kaimaras, D; Tsokana, C N; Iliadou, P; Spyrou, V; Tzani, M; Birtsas, P; Kostoglou, P; Sokos, C; Doudounakis, S; Yon, L; Hannant, D; Artois, M; Tsiodras, S; Hadjichristodoulou, C; Billinis, C

2016-10-01

The objectives of this work were (i) geographical analysis of the 2012-2014 outbreak of rabies in Greece using GIS and (ii) comparative analysis of animal cases with data of potential human exposure to rabies together with environmental data, in order to provide information for risk assessment, effective monitoring and control. Most animal cases (40/48) involved red foxes, while domestic animals were also diagnosed with rabies. Overall, 80% of the cases were diagnosed in central northern Greece; 75% of the cases were diagnosed in low altitudes (<343·5 m), within a distance of 1 km from human settlements. Median distance from livestock farms was 201·25 m. Most people potentially exposed to rabies (889/1060) presented with dog bite injuries. Maximum entropy analysis revealed that distance from farms contributed the highest percentage in defining environmental niche profiles for rabid foxes. Oral vaccination programmes were implemented in 24 administrative units of the country during 2013 and 2014, covering a total surface area of ~60 000 km2. Rabies re-occurrence in Greece emphasizes the need for ongoing surveillance in cross-border areas and in areas with intense human activity.

Creation of medicinal chemistry learning communities through enhanced technology and interdisciplinary collaboration.

PubMed

Henriksen, Brian; Roche, Victoria

2012-10-12

Objectives. To build an integrated medicinal chemistry learning community of campus and distance pharmacy students though the use of innovative technology and interdisciplinary teaching.Design. Mechanisms were implemented to bring distance students into campus-based medicinal chemistry classrooms in real time, stimulate interaction between instructors and various student cohorts, and promote group work during class. Also, pharmacy clinician colleagues were recruited to contribute to the teaching of the 3 medicinal chemistry courses.Assessment. Student perceptions on the value of technology to build community and advance learning were gleaned from course evaluations, in class feedback, and conversations with class officers and student groups. Responses on a survey of second-year students confirmed the benefits of interdisciplinary content integration on engagement and awareness of the connection between drug chemistry and pharmacy practice. A survey of clinician colleagues who contributed to teaching the 3 medicinal chemistry courses found their views were similar to those of students.Conclusions. The purposeful use of technology united learners, fostered communication, and advanced content comprehension in 3 medicinal chemistry courses taught to campus and distance students. Teaching collaboration with pharmacy clinicians enhanced learner interest in course content and provided insight into the integrated nature of the profession of pharmacy.

The proportion of the face in younger adults using the thumb rule of Leonardo da Vinci.

PubMed

Oguz, O

1996-01-01

The present study was conducted to examine whether the thumb rule of Leonardo da Vinci could be an objective method in the determination of the natural and artistic proportions of human face. In this study, a sample of 400 subjects (200 male and 200 female, 22-25 years old) was used. Measurements were made of the length of thumb, the length of ear, the approximate distances between the hair line and the glabella or eyebrows, between the glabella or eyebrows and the tip of the nose and the distance between the nose and the chin, and the distance between the ear and the lateral aspect of the eye. The results obtained in the males and females showed significant (p < 0.01) correlations between the length of thumb and the proportions of the face examined in the study. Additionally, the height of the face was found to be almost three times the length of the thumb. However, the measurements obtained from female subjects were on average smaller than those taken from males. The results obtained in this experiment could be of value in understanding of the evaluation of the face for the people working in plastic surgery or art.

Vocational Education Distance Learning Delivery System. Final Report.

ERIC Educational Resources Information Center

Hardy, Darcy Walsh

A project was conducted to identify criteria and procedures for using a distance learning delivery system at the University of Texas TeleLearning Center to teach Health Occupations II to high school seniors. Another objective was expanding the current distance learning program for health occupations to include between 15 and 20 school districts.…

[Pilot study of the acoustic values of the vowels in Spanish as indicators of the severity of dysarthria].

PubMed

Delgado-Hernandez, J

2017-02-01

The acoustic analysis is a tool that provides objective data on changes of speech in dysarthria. To evaluate, in the ataxic dysarthria, the relationship between the vowel space area (VSA), the formant centralization ratio (FCR) and the mean of the primary distances with the speech intelligibility. A sample of fourteen Spanish speakers, ten with dysarthria and four controls, was used. The values of first and second formants in 140 vowels extracted of 140 words were analyzed. To calculate the level of intelligibility seven listeners were involved and a task of identification verbal stimuli was used. The dysarthric subjects have less contrast between middle and high vowels and between back vowels. Significant differences in the VSA, FCR and mean of the primary distances compared to control subjects (p = 0.007, 0.005 and 0.030, respectively) are observed. Regression analysis show the relationship between VSA and the mean of primary distances with the level of speech intelligibility (r = 0.60 and 0.74, respectively). Ataxic dysarthria subjects have lower contrast and vowel centralization in carrying out the vowels. The acoustic measures studied in this preliminary work have a high sensitivity in the detection of dysarthria but only the VSA and the mean of primary distances provide information on the severity of this type of speech disturbance.

Minimum distance classification in remote sensing

NASA Technical Reports Server (NTRS)

Wacker, A. G.; Landgrebe, D. A.

1972-01-01

The utilization of minimum distance classification methods in remote sensing problems, such as crop species identification, is considered. Literature concerning both minimum distance classification problems and distance measures is reviewed. Experimental results are presented for several examples. The objective of these examples is to: (a) compare the sample classification accuracy of a minimum distance classifier, with the vector classification accuracy of a maximum likelihood classifier, and (b) compare the accuracy of a parametric minimum distance classifier with that of a nonparametric one. Results show the minimum distance classifier performance is 5% to 10% better than that of the maximum likelihood classifier. The nonparametric classifier is only slightly better than the parametric version.

Toot Your Own Horn! Share Your Successes through Publication, Conferences, Awards, and Professional Development

ERIC Educational Resources Information Center

Schulte, Marthann

2016-01-01

Working at a distance brings several benefits, often offset by several detriments. One aspect of working at a distance is the difficulty in sharing successes and promoting accolades. These successes may be personal, team, program, or institutional. But, as a distance worker it can seem daunting or even futile when attempting to "toot your own…

The finite body triangulation: algorithms, subgraphs, homogeneity estimation and application.

PubMed

Carson, Cantwell G; Levine, Jonathan S

2016-09-01

The concept of a finite body Dirichlet tessellation has been extended to that of a finite body Delaunay 'triangulation' to provide a more meaningful description of the spatial distribution of nonspherical secondary phase bodies in 2- and 3-dimensional images. A finite body triangulation (FBT) consists of a network of minimum edge-to-edge distances between adjacent objects in a microstructure. From this is also obtained the characteristic object chords formed by the intersection of the object boundary with the finite body tessellation. These two sets of distances form the basis of a parsimonious homogeneity estimation. The characteristics of the spatial distribution are then evaluated with respect to the distances between objects and the distances within them. Quantitative analysis shows that more physically representative distributions can be obtained by selecting subgraphs, such as the relative neighbourhood graph and the minimum spanning tree, from the finite body tessellation. To demonstrate their potential, we apply these methods to 3-dimensional X-ray computed tomographic images of foamed cement and their 2-dimensional cross sections. The Python computer code used to estimate the FBT is made available. Other applications for the algorithm - such as porous media transport and crack-tip propagation - are also discussed. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Tactical decisions for changeable cuttlefish camouflage: visual cues for choosing masquerade are relevant from a greater distance than visual cues used for background matching.

PubMed

Buresch, Kendra C; Ulmer, Kimberly M; Cramer, Corinne; McAnulty, Sarah; Davison, William; Mäthger, Lydia M; Hanlon, Roger T

2015-10-01

Cuttlefish use multiple camouflage tactics to evade their predators. Two common tactics are background matching (resembling the background to hinder detection) and masquerade (resembling an uninteresting or inanimate object to impede detection or recognition). We investigated how the distance and orientation of visual stimuli affected the choice of these two camouflage tactics. In the current experiments, cuttlefish were presented with three visual cues: 2D horizontal floor, 2D vertical wall, and 3D object. Each was placed at several distances: directly beneath (in a circle whose diameter was one body length (BL); at zero BL [(0BL); i.e., directly beside, but not beneath the cuttlefish]; at 1BL; and at 2BL. Cuttlefish continued to respond to 3D visual cues from a greater distance than to a horizontal or vertical stimulus. It appears that background matching is chosen when visual cues are relevant only in the immediate benthic surroundings. However, for masquerade, objects located multiple body lengths away remained relevant for choice of camouflage. © 2015 Marine Biological Laboratory.

Underwater detection by using ultrasonic sensor

NASA Astrophysics Data System (ADS)

Bakar, S. A. A.; Ong, N. R.; Aziz, M. H. A.; Alcain, J. B.; Haimi, W. M. W. N.; Sauli, Z.

2017-09-01

This paper described the low cost implementation of hardware and software in developing the system of ultrasonic which can visualize the feedback of sound in the form of measured distance through mobile phone and monitoring the frequency of detection by using real time graph of Java application. A single waterproof transducer of JSN-SR04T had been used to determine the distance of an object based on operation of the classic pulse echo detection method underwater. In this experiment, the system was tested by placing the housing which consisted of Arduino UNO, Bluetooth module of HC-06, ultrasonic sensor and LEDs at the top of the box and the transducer was immersed in the water. The system which had been tested for detection in vertical form was found to be capable of reporting through the use of colored LEDs as indicator to the relative proximity of object distance underwater form the sensor. As a conclusion, the system can detect the presence of an object underwater within the range of ultrasonic sensor and display the measured distance onto the mobile phone and the real time graph had been successfully generated.

Assessment of Multiresolution Segmentation for Extracting Greenhouses from WORLDVIEW-2 Imagery

NASA Astrophysics Data System (ADS)

Aguilar, M. A.; Aguilar, F. J.; García Lorca, A.; Guirado, E.; Betlej, M.; Cichon, P.; Nemmaoui, A.; Vallario, A.; Parente, C.

2016-06-01

The latest breed of very high resolution (VHR) commercial satellites opens new possibilities for cartographic and remote sensing applications. In this way, object based image analysis (OBIA) approach has been proved as the best option when working with VHR satellite imagery. OBIA considers spectral, geometric, textural and topological attributes associated with meaningful image objects. Thus, the first step of OBIA, referred to as segmentation, is to delineate objects of interest. Determination of an optimal segmentation is crucial for a good performance of the second stage in OBIA, the classification process. The main goal of this work is to assess the multiresolution segmentation algorithm provided by eCognition software for delineating greenhouses from WorldView- 2 multispectral orthoimages. Specifically, the focus is on finding the optimal parameters of the multiresolution segmentation approach (i.e., Scale, Shape and Compactness) for plastic greenhouses. The optimum Scale parameter estimation was based on the idea of local variance of object heterogeneity within a scene (ESP2 tool). Moreover, different segmentation results were attained by using different combinations of Shape and Compactness values. Assessment of segmentation quality based on the discrepancy between reference polygons and corresponding image segments was carried out to identify the optimal setting of multiresolution segmentation parameters. Three discrepancy indices were used: Potential Segmentation Error (PSE), Number-of-Segments Ratio (NSR) and Euclidean Distance 2 (ED2).

VizieR Online Data Catalog: R absolute magnitudes of Kuiper Belt objects (Peixinho+, 2012)

NASA Astrophysics Data System (ADS)

Peixinho, N.; Delsanti, A.; Guilbert-Lepoutre, A.; Gafeira, R.; Lacerda, P.

2012-06-01

Compilation of absolute magnitude HRα, B-R color spectral features used in this work. For each object, we computed the average color index from the different papers presenting data obtained simultaneously in B and R bands (e.g. contiguous observations within a same night). When individual R apparent magnitude and date were available, we computed the HRα=R-5log(r Delta), where R is the R-band magnitude, r and Delta are the helio- and geocentric distances at the time of observation in AU, respectively. When V and V-R colors were available, we derived an R and then HRα value. We did not correct for the phase-angle α effect. This table includes also spectral information on the presence of water ice, methanol, methane, or confirmed featureless spectra, as available in the literature. We highlight only the cases with clear bands in the spectrum, which were reported/confirmed by some other work. The 1st column indicates the object identification number and name or provisional designation; the 2nd column indicates the dynamical class; the 3rd column indicates the average HRα value and 1-σ error bars; the 4th column indicates the average $B-R$ color and 1-σ error bars; the 5th column indicates the most important spectral features detected; and the 6th column points to the bibliographic references used for each object. (3 data files).

THE BOLOCAM GALACTIC PLANE SURVEY. XII. DISTANCE CATALOG EXPANSION USING KINEMATIC ISOLATION OF DENSE MOLECULAR CLOUD STRUCTURES WITH {sup 13}CO(1-0)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellsworth-Bowers, Timothy P.; Glenn, Jason; Rosolowsky, Erik

2015-01-20

We present an expanded distance catalog for 1710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO{sup +}(3-2), NH{sub 3}(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey (GRS) {sup 13}CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region ofmore » the GRS {sup 13}CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of {sup 13}CO matched to the BGPS source. For objects with a HCO{sup +}(3-2) velocity, ≈95% of the new {sup 13}CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and H II regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties ≲ 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centaurus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.« less

Collection efficiency and acceptance maps of electron detectors for understanding signal detection on modern scanning electron microscopy.

PubMed

Agemura, Toshihide; Sekiguchi, Takashi

2018-02-01

Collection efficiency and acceptance maps of typical detectors in modern scanning electron microscopes (SEMs) were investigated. Secondary and backscattered electron trajectories from a specimen to through-the-lens and under-the-lens detectors placed on an electron optical axis and an Everhart-Thornley detector mounted on a specimen chamber were simulated three-dimensionally. The acceptance maps were drawn as the relationship between the energy and angle of collected electrons under different working distances. The collection efficiency considering the detector sensitivity was also estimated for the various working distances. These data indicated that the acceptance maps and collection efficiency are keys to understand the detection mechanism and image contrast for each detector in the modern SEMs. Furthermore, the working distance is the dominant parameter because electron trajectories are drastically changed with the working distance.

Cognitive and Anatomical Underpinnings of the Conceptual Knowledge for Common Objects and Familiar People: A Repetitive Transcranial Magnetic Stimulation Study

PubMed Central

Campanella, Fabio; Fabbro, Franco; Urgesi, Cosimo

2013-01-01

Several studies have addressed the issue of how knowledge of common objects is organized in the brain, whereas the cognitive and anatomical underpinnings of familiar people knowledge have been less explored. Here we applied repetitive transcranial magnetic stimulation (rTMS) over the left and right temporal poles before asking healthy individuals to perform a speeded word-to-picture matching task using familiar people and common objects as stimuli. We manipulated two widely used semantic variables, namely the semantic distance and the familiarity of stimuli, to assess whether the semantic organization of familiar people knowledge is similar to that of common objects. For both objects and faces we reliably found semantic distance and familiarity effects, with less accurate and slower responses for stimulus pairs that were more closely related and less familiar. However, the effects of semantic variables differed across categories, with semantic distance effects larger for objects and familiarity effects larger for faces, suggesting that objects and faces might share a partially comparable organization of their semantic representations. The application of rTMS to the left temporal pole modulated, for both categories, semantic distance, but not familiarity effects, revealing that accessing object and face concepts might rely on overlapping processes within left anterior temporal regions. Crucially, rTMS of the left temporal pole affected only the recognition of pairs of stimuli that could be discriminated at specific levels of categorization (e.g., two kitchen tools or two famous persons), with no effect for discriminations at either superordinate or individual levels. Conversely, rTMS of the right temporal pole induced an overall slowing of reaction times that positively correlated with the visual similarity of the stimuli, suggesting a more perceptual rather than semantic role of the right anterior temporal regions. Results are discussed in the light of current models of face and object semantic representations in the brain. PMID:23704999

Multisensory integration and the concert experience: An overview of how visual stimuli can affect what we hear

NASA Astrophysics Data System (ADS)

Hyde, Jerald R.

2004-05-01

It is clear to those who ``listen'' to concert halls and evaluate their degree of acoustical success that it is quite difficult to separate the acoustical response at a given seat from the multi-modal perception of the whole event. Objective concert hall data have been collected for the purpose of finding a link with their related subjective evaluation and ultimately with the architectural correlates which produce the sound field. This exercise, while important, tends to miss the point that a concert or opera event utilizes all the senses of which the sound field and visual stimuli are both major contributors to the experience. Objective acoustical factors point to visual input as being significant in the perception of ``acoustical intimacy'' and with the perception of loudness versus distance in large halls. This paper will review the evidence of visual input as a factor in what we ``hear'' and introduce concepts of perceptual constancy, distance perception, static and dynamic visual stimuli, and the general process of the psychology of the integrated experience. A survey of acousticians on their opinions about the auditory-visual aspects of the concert hall experience will be presented. [Work supported in part from the Veneklasen Research Foundation and Veneklasen Associates.

AMICO: optimized detection of galaxy clusters in photometric surveys

NASA Astrophysics Data System (ADS)

Bellagamba, Fabio; Roncarelli, Mauro; Maturi, Matteo; Moscardini, Lauro

2018-02-01

We present Adaptive Matched Identifier of Clustered Objects (AMICO), a new algorithm for the detection of galaxy clusters in photometric surveys. AMICO is based on the Optimal Filtering technique, which allows to maximize the signal-to-noise ratio (S/N) of the clusters. In this work, we focus on the new iterative approach to the extraction of cluster candidates from the map produced by the filter. In particular, we provide a definition of membership probability for the galaxies close to any cluster candidate, which allows us to remove its imprint from the map, allowing the detection of smaller structures. As demonstrated in our tests, this method allows the deblending of close-by and aligned structures in more than 50 per cent of the cases for objects at radial distance equal to 0.5 × R200 or redshift distance equal to 2 × σz, being σz the typical uncertainty of photometric redshifts. Running AMICO on mocks derived from N-body simulations and semi-analytical modelling of the galaxy evolution, we obtain a consistent mass-amplitude relation through the redshift range of 0.3 < z < 1, with a logarithmic slope of ∼0.55 and a logarithmic scatter of ∼0.14. The fraction of false detections is steeply decreasing with S/N and negligible at S/N > 5.

Estado evolutivo de estrellas con fenómeno B[e

NASA Astrophysics Data System (ADS)

Aidelman, Y. J.; Cidale, L.; Borges Fernandes, M.; Kraus, M.

The B[e] phenomenon is related to certain peculiar features observed in the spectrum of some B stars, which are mainly linked to the physical conditions of their circumstellar medium. As these stars are embedded in dense and optically thick circumstellar media, the determination of the spectral type and luminosity class of the central objects is quite difficult. As a consequence, their evolutionary stage and distances present huge uncertainties. In this work we study 4 B[e] stars and discuss their stellar fundamental parameters and evolutionary stages using the BCD spectrophotometric system. FULL TEXT IN SPANISH

Mapping racism.

PubMed

Moss, Donald B

2006-01-01

The author uses the metaphor of mapping to illuminate a structural feature of racist thought, locating the degraded object along vertical and horizontal axes. These axes establish coordinates of hierarchy and of distance. With the coordinates in place, racist thought begins to seem grounded in natural processes. The other's identity becomes consolidated, and parochialism results. The use of this kind of mapping is illustrated via two patient vignettes. The author presents Freud's (1905, 1927) views in relation to such a "mapping" process, as well as Adorno's (1951) and Baldwin's (1965). Finally, the author conceptualizes the crucial status of primitivity in the workings of racist thought.

Dual-axis confocal microscope for high-resolution in vivo imaging

PubMed Central

Wang, Thomas D.; Mandella, Michael J.; Contag, Christopher H.; Kino, Gordon S.

2007-01-01

We describe a novel confocal microscope that uses separate low-numerical-aperture objectives with the illumination and collection axes crossed at angle θ from the midline. This architecture collects images in scattering media with high transverse and axial resolution, long working distance, large field of view, and reduced noise from scattered light. We measured transverse and axial (FWHM) resolution of 1.3 and 2.1 μm, respectively, in free space, and confirm subcellular resolution in excised esophageal mucosa. The optics may be scaled to millimeter dimensions and fiber coupled for collection of high-resolution images in vivo. PMID:12659264

Method and apparatus for making absolute range measurements

DOEpatents

Allison, Stephen W.; Cates, Michael R.; Key, William S.; Sanders, Alvin J.; Earl, Dennis D.

1999-01-01

This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through an object which causes it to be split (hereinafter referred to as a "beamsplitter"), and then to a target. The beam is reflected from the target onto a screen containing an aperture spaced a known distance from the beamsplitter. The aperture is sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector, spaced a known distance from the screen. The detector detects the central intensity of the beam. The distance from the object which causes the beam to be split to the target can then be calculated based upon the known wavelength, aperture radius, beam intensity, and distance from the detector to the screen. Several apparatus embodiments are disclosed for practicing the method embodiments of the present invention.

Method and apparatus for making absolute range measurements

DOEpatents

Allison, S.W.; Cates, M.R.; Key, W.S.; Sanders, A.J.; Earl, D.D.

1999-06-22

This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through an object which causes it to be split (hereinafter referred to as a beam splitter''), and then to a target. The beam is reflected from the target onto a screen containing an aperture spaced a known distance from the beam splitter. The aperture is sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector, spaced a known distance from the screen. The detector detects the central intensity of the beam. The distance from the object which causes the beam to be split to the target can then be calculated based upon the known wavelength, aperture radius, beam intensity, and distance from the detector to the screen. Several apparatus embodiments are disclosed for practicing the method embodiments of the present invention. 9 figs.

Concept for tremor compensation for a handheld OCT-laryngoscope

NASA Astrophysics Data System (ADS)

Donner, Sabine; Deutsch, Stefanie; Bleeker, Sebastian; Ripken, Tammo; Krüger, Alexander

2013-06-01

Optical coherence tomography (OCT) is a non-invasive imaging technique which can create optical tissue sections, enabling diagnosis of vocal cord tissue. To take full advantage from the non-contact imaging technique, OCT was adapted to an indirect laryngoscope to work on awake patients. Using OCT in a handheld diagnostic device the challenges of rapid working distance adjustment and tracking of axial motion arise. The optical focus of the endoscopic sample arm and the reference-arm length can be adjusted in a range of 40 mm to 90 mm. Automatic working distance adjustment is based on image analysis of OCT B-scans which identifies off depth images as well as position errors. The movable focal plane and reference plane are used to adjust working distance to match the sample depth and stabilise the sample in the desired axial position of the OCT scans. The autofocus adjusts the working distance within maximum 2.7 seconds for the maximum initial displacement of 40 mm. The amplitude of hand tremor during 60 s handheld scanning was reduced to 50 % and it was shown that the image stabilisation keeps the position error below 0.5 mm. Fast automatic working distance adjustment is crucial to minimise the duration of the diagnostic procedure. The image stabilisation compensates relative axial movements during handheld scanning.

Image Formation in Lenses and Mirrors, a Complete Representation

ERIC Educational Resources Information Center

Bartlett, Albert A.

1976-01-01

Provides tables and graphs that give a complete and simple picture of the relationships of image distance, object distance, and magnification in all formations of images by simple lenses and mirrors. (CP)

Older driver estimates of driving exposure compared to in-vehicle data in the Candrive II study.

PubMed

Porter, Michelle M; Smith, Glenys A; Cull, Andrew W; Myers, Anita M; Bédard, Michel; Gélinas, Isabelle; Mazer, Barbara L; Marshall, Shawn C; Naglie, Gary; Rapoport, Mark J; Tuokko, Holly A; Vrkljan, Brenda H

2015-01-01

Most studies on older adults' driving practices have relied on self-reported information. With technological advances it is now possible to objectively measure the everyday driving of older adults in their own vehicles over time. The purpose of this study was to examine the ability of older drivers to accurately estimate their kilometers driven over one year relative to objectively measured driving exposure. A subsample (n = 159 of 928; 50.9% male) of Candrive II participants (age ≥ 70 years of age) was used in these analyses based on strict criteria for data collected from questionnaires as well as an OttoView-CD Autonomous Data Logging Device installed in their vehicle, over the first year of the prospective cohort study. Although there was no significant difference overall between the self-reported and objectively measured distance categories, only moderate agreement was found (weighted kappa = 0.57; 95% confidence interval, 0.47-0.67). Almost half (45.3%) chose the wrong distance category, and some people misestimated their distance driven by up to 20,000 km. Those who misjudged in the low mileage group (≤5000 km) consistently underestimated, whereas the reverse was found for those in the high distance categories (≥ 20,000); that is, they always overestimated their driving distance. Although self-reported driving distance categories may be adequate for studies entailing broad group comparisons, caution should be used in interpreting results. Use of self-reported estimates for individual assessments should be discouraged.

ON EDGE CHIPPING TESTING AND SOME PERSONAL PERSPECTIVES ON THE STATE OF THE ART OF MECHANICAL TESTING

PubMed Central

Quinn, G. D.

2014-01-01

Objective The edge chipping test is used to measure the fracture resistance of dental restoration ceramics and resin composites. This paper focuses on the progress of evaluating chipping resistance of these materials and also on the progress of standardization of this test method. This paper also makes observations about the state of the art of mechanical testing of ceramic and composite restorative materials in general. Interlaboratory comparative studies (“round robins”) are recommended. Methods An edge chipping machine was used to evaluate dozens of materials including porcelains, glass ceramics, aluminas, zirconias, filled resin-composites, new hybrid ceramic-resin composites, laminated composite ceramics, and even polymethyl methacrylate based denture materials. Force versus distance data were collected over a broad range with different indenters. Several chipping resistance parameters were quantified. Results Older restorative materials such as feldspathic porcelains and veneering materials had limited chipping resistance, but more modern ceramics and filled composites show significant improvements. A yttria-partially stabilized zirconia had the greatest resistance to chipping. Much of the early work on edge chipping resistance of brittle materials emphasized linear force versus distance trends obtained with relatively blunt Rockwell C indenters. More recently, trends for dental restorative materials with alternative sharper indenters have been nonlinear. A new phenomenological model with a simple quadratic function fits all data exceptionally well. It is loosely based on an energy balance between indenter work and fracture and deformation energies in the chipped material. Significance Although a direct comparison of our laboratory scale tests on idealized simple geometries to clinical outcomes has not yet been done, anecdotal evidence suggests the procedure does produce clinically relevant rankings and outcomes. Despite the variations in the trends and indenters, comparisons between materials can easily be made by chipping convenient block-shaped specimens with sharp conical 120°, Vickers, or Rockwell C indenters at a defined edge distance of 0.5 mm. Broad distance ranges are recommended for trend evaluation. This work has provided important information for standardization. PMID:25244927

Social scaling of extrapersonal space: target objects are judged as closer when the reference frame is a human agent with available movement potentialities.

PubMed

Fini, C; Brass, M; Committeri, G

2015-01-01

Space perception depends on our motion potentialities and our intended actions are affected by space perception. Research on peripersonal space (the space in reaching distance) shows that we perceive an object as being closer when we (Witt, Proffitt, & Epstein, 2005; Witt & Proffitt, 2008) or another actor (Costantini, Ambrosini, Sinigaglia, & Gallese, 2011; Bloesch, Davoli, Roth, Brockmole, & Abrams, 2012) can interact with it. Similarly, an object only triggers specific movements when it is placed in our peripersonal space (Costantini, Ambrosini, Tieri, Sinigaglia, & Committeri, 2010) or in the other's peripersonal space (Costantini, Committeri, & Sinigaglia, 2011; Cardellicchio, Sinigaglia, & Costantini, 2013). Moreover, also the extrapersonal space (the space outside reaching distance) seems to be perceived in relation to our movement capabilities: the more effort it takes to cover a distance, the greater we perceive the distance to be (Proffitt, Stefanucci, Banton, & Epstein, 2003; Sugovic & Witt, 2013). However, not much is known about the influence of the other's movement potentialities on our extrapersonal space perception. Three experiments were carried out investigating the categorization of distance in extrapersonal space using human or non-human allocentric reference frames (RF). Subjects were asked to judge the distance ("Near" or "Far") of a target object (a beach umbrella) placed at progressively increasing or decreasing distances until a change from near to far or vice versa was reported. In the first experiment we found a significant "Near space extension" when the allocentric RF was a human virtual agent instead of a static, inanimate object. In the second experiment we tested whether the "Near space extension" depended on the anatomical structure of the RF or its movement potentialities by adding a wooden dummy. The "Near space extension" was only observed for the human agent but not for the dummy. Finally, to rule out the possibility that the effect was simply due to a line-of-sight mechanism (visual perspective taking) we compared the human agent free to move with the same agent tied to a pole with a rope, thus reducing movement potentialities while maintaining equal visual accessibility. The "Near space extension" disappeared when this manipulation was introduced, showing that movement potentialities are the relevant factor for such an effect. Our results demonstrate for the first time that during allocentric distance judgments within extrapersonal space, we implicitly process the movement potentialities of the RF. A target object is perceived as being closer when the allocentric RF is a human with available movement potentialities, suggesting a mechanism of social scaling of extrapersonal space processing. Copyright © 2014. Published by Elsevier B.V.

An approach to multiobjective optimization of rotational therapy. II. Pareto optimal surfaces and linear combinations of modulated blocked arcs for a prostate geometry.

PubMed

Pardo-Montero, Juan; Fenwick, John D

2010-06-01

The purpose of this work is twofold: To further develop an approach to multiobjective optimization of rotational therapy treatments recently introduced by the authors [J. Pardo-Montero and J. D. Fenwick, "An approach to multiobjective optimization of rotational therapy," Med. Phys. 36, 3292-3303 (2009)], especially regarding its application to realistic geometries, and to study the quality (Pareto optimality) of plans obtained using such an approach by comparing them with Pareto optimal plans obtained through inverse planning. In the previous work of the authors, a methodology is proposed for constructing a large number of plans, with different compromises between the objectives involved, from a small number of geometrically based arcs, each arc prioritizing different objectives. Here, this method has been further developed and studied. Two different techniques for constructing these arcs are investigated, one based on image-reconstruction algorithms and the other based on more common gradient-descent algorithms. The difficulty of dealing with organs abutting the target, briefly reported in previous work of the authors, has been investigated using partial OAR unblocking. Optimality of the solutions has been investigated by comparison with a Pareto front obtained from inverse planning. A relative Euclidean distance has been used to measure the distance of these plans to the Pareto front, and dose volume histogram comparisons have been used to gauge the clinical impact of these distances. A prostate geometry has been used for the study. For geometries where a blocked OAR abuts the target, moderate OAR unblocking can substantially improve target dose distribution and minimize hot spots while not overly compromising dose sparing of the organ. Image-reconstruction type and gradient-descent blocked-arc computations generate similar results. The Pareto front for the prostate geometry, reconstructed using a large number of inverse plans, presents a hockey-stick shape comprising two regions: One where the dose to the target is close to prescription and trade-offs can be made between doses to the organs at risk and (small) changes in target dose, and one where very substantial rectal sparing is achieved at the cost of large target underdosage. Plans computed following the approach using a conformal arc and four blocked arcs generally lie close to the Pareto front, although distances of some plans from high gradient regions of the Pareto front can be greater. Only around 12% of plans lie a relative Euclidean distance of 0.15 or greater from the Pareto front. Using the alternative distance measure of Craft ["Calculating and controlling the error of discrete representations of Pareto surfaces in convex multi-criteria optimization," Phys. Medica (to be published)], around 2/5 of plans lie more than 0.05 from the front. Computation of blocked arcs is quite fast, the algorithms requiring 35%-80% of the running time per iteration needed for conventional inverse plan computation. The geometry-based arc approach to multicriteria optimization of rotational therapy allows solutions to be obtained that lie close to the Pareto front. Both the image-reconstruction type and gradient-descent algorithms produce similar modulated arcs, the latter one perhaps being preferred because it is more easily implementable in standard treatment planning systems. Moderate unblocking provides a good way of dealing with OARs which abut the PTV. Optimization of geometry-based arcs is faster than usual inverse optimization of treatment plans, making this approach more rapid than an inverse-based Pareto front reconstruction.

Visualizing Similarity of Appearance by Arrangement of Cards

PubMed Central

Nakatsuji, Nao; Ihara, Hisayasu; Seno, Takeharu; Ito, Hiroshi

2016-01-01

This study proposes a novel method to extract the configuration of the psychological space by directly measuring subjects' similarity rating without computational work. Although multidimensional scaling (MDS) is well-known as a conventional method for extracting the psychological space, the method requires many pairwise evaluations. The times taken for evaluations increase in proportion to the square of the number of objects in MDS. The proposed method asks subjects to arrange cards on a poster sheet according to the degree of similarity of the objects. To compare the performance of the proposed method with the conventional one, we developed similarity maps of typefaces through the proposed method and through non-metric MDS. We calculated the trace correlation coefficient among all combinations of the configuration for both methods to evaluate the degree of similarity in the obtained configurations. The threshold value of trace correlation coefficient for statistically discriminating similar configuration was decided based on random data. The ratio of the trace correlation coefficient exceeding the threshold value was 62.0% so that the configurations of the typefaces obtained by the proposed method closely resembled those obtained by non-metric MDS. The required duration for the proposed method was approximately one third of the non-metric MDS's duration. In addition, all distances between objects in all the data for both methods were calculated. The frequency for the short distance in the proposed method was lower than that of the non-metric MDS so that a relatively small difference was likely to be emphasized among objects in the configuration by the proposed method. The card arrangement method we here propose, thus serves as a easier and time-saving tool to obtain psychological structures in the fields related to similarity of appearance. PMID:27242611

Application of ultrasonic sensor for measuring distances in robotics

NASA Astrophysics Data System (ADS)

Zhmud, V. A.; Kondratiev, N. O.; Kuznetsov, K. A.; Trubin, V. G.; Dimitrov, L. V.

2018-05-01

Ultrasonic sensors allow us to equip robots with a means of perceiving surrounding objects, an alternative to technical vision. Humanoid robots, like robots of other types, are, first, equipped with sensory systems similar to the senses of a human. However, this approach is not enough. All possible types and kinds of sensors should be used, including those that are similar to those of other animals and creations (in particular, echolocation in dolphins and bats), as well as sensors that have no analogues in the wild. This paper discusses the main issues that arise when working with the HC-SR04 ultrasound rangefinder based on the STM32VLDISCOVERY evaluation board. The characteristics of similar modules for comparison are given. A subroutine for working with the sensor is given.

Effects of Iris Surface Curvature on Iris Recognition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Joseph T; Flynn, Patrick J; Bowyer, Kevin W

To focus on objects at various distances, the lens of the eye must change shape to adjust its refractive power. This change in lens shape causes a change in the shape of the iris surface which can be measured by examining the curvature of the iris. This work isolates the variable of iris curvature in the recognition process and shows that differences in iris curvature degrade matching ability. To our knowledge, no other work has examined the effects of varying iris curvature on matching ability. To examine this degradation, we conduct a matching experiment across pairs of images with varyingmore » degrees of iris curvature differences. The results show a statistically signi cant degradation in matching ability. Finally, the real world impact of these ndings is discussed« less

Science and the public self

USGS Publications Warehouse

Frodeman, R.

2000-01-01

Scientists employed by agencies of the US government (and by extension, those working at universities who are recipients of federal grants) have distinctive responsibilities to the community that supports their work. Traditionally, such public scientists retreated behind a veil of objectivity thought to define scientific knowledge. But this approach today fails on both epistemological and political grounds. Most striking is the fact that the very stance of principled distance from societal debates has opened the scientist to charges of irrelevance. What is the distinctive role of federal science agencies in society? Is there a way out of the dilemma in which government scientists are seen as irrelevant, or if relevant, biased? It is argued here that the notion of a public self offers a means out of this dilemma. (C) 2000 Published by Elsevier Science Ltd.

Cognitive Load Theory and the Use of Worked Examples as an Instructional Strategy in Physics for Distance Learners: A Preliminary Study

ERIC Educational Resources Information Center

Saw, Kim Guan

2017-01-01

This article revisits the cognitive load theory to explore the use of worked examples to teach a selected topic in a higher level undergraduate physics course for distance learners at the School of Distance Education, Universiti Sains Malaysia. With a break of several years from receiving formal education and having only minimum science…

Does Distance Matter? Distance to Mammography Facilities and Stage at Diagnosis of Breast Cancer in Kentucky

ERIC Educational Resources Information Center

Huang, Bin; Dignan, Mark; Han, Daikwon; Johnson, Owen

2009-01-01

Background: National and regional data indicate that breast cancer early detection is low in Kentucky, especially rural regions, perhaps because access to mammography services can be problematic. Objective: This study examined the distance between residences of women diagnosed with breast cancer and the nearest mammography facility, as a risk…

Building Academic Quality in Distance Higher Education. A Monograph in Higher Education Evaluation and Policy.

ERIC Educational Resources Information Center

Chacon-Duque, Fabio J.

The factors that determine course completion and achievement in college distance education were investigated using a sample of 25 courses offered through the Independent Learning Program at the Pennsylvania State University. The main objective was to develop a multivariate model to explain and predict outcomes of distance education. Additional…

Multidimensional Unfolding by Nonmetric Multidimensional Scaling of Spearman Distances in the Extended Permutation Polytope

ERIC Educational Resources Information Center

Van Deun, Katrijn; Heiser, Willem J.; Delbeke, Luc

2007-01-01

A multidimensional unfolding technique that is not prone to degenerate solutions and is based on multidimensional scaling of a complete data matrix is proposed: distance information about the unfolding data and about the distances both among judges and among objects is included in the complete matrix. The latter information is derived from the…

How Far Is "Near"? Inferring Distance from Spatial Descriptions

ERIC Educational Resources Information Center

Carlson, Laura A.; Covey, Eric S.

2005-01-01

A word may mean different things in different contexts. The current study explored the changing denotations of spatial terms, focusing on how the distance inferred from a spatial description varied as a function of the size of the objects being spatially related. We examined both terms that explicitly convey distance (i.e., topological terms such…

3D High Resolution Mesh Deformation Based on Multi Library Wavelet Neural Network Architecture

NASA Astrophysics Data System (ADS)

Dhibi, Naziha; Elkefi, Akram; Bellil, Wajdi; Amar, Chokri Ben

2016-12-01

This paper deals with the features of a novel technique for large Laplacian boundary deformations using estimated rotations. The proposed method is based on a Multi Library Wavelet Neural Network structure founded on several mother wavelet families (MLWNN). The objective is to align features of mesh and minimize distortion with a fixed feature that minimizes the sum of the distances between all corresponding vertices. New mesh deformation method worked in the domain of Region of Interest (ROI). Our approach computes deformed ROI, updates and optimizes it to align features of mesh based on MLWNN and spherical parameterization configuration. This structure has the advantage of constructing the network by several mother wavelets to solve high dimensions problem using the best wavelet mother that models the signal better. The simulation test achieved the robustness and speed considerations when developing deformation methodologies. The Mean-Square Error and the ratio of deformation are low compared to other works from the state of the art. Our approach minimizes distortions with fixed features to have a well reconstructed object.

Investigation on Multiple Algorithms for Multi-Objective Optimization of Gear Box

NASA Astrophysics Data System (ADS)

Ananthapadmanabhan, R.; Babu, S. Arun; Hareendranath, KR; Krishnamohan, C.; Krishnapillai, S.; A, Krishnan

2016-09-01

The field of gear design is an extremely important area in engineering. In this work a spur gear reduction unit is considered. A review of relevant literatures in the area of gear design indicates that compact design of gearbox involves a complicated engineering analysis. This work deals with the simultaneous optimization of the power and dimensions of a gearbox, which are of conflicting nature. The focus is on developing a design space which is based on module, pinion teeth and face-width by using MATLAB. The feasible points are obtained through different multi-objective algorithms using various constraints obtained from different novel literatures. Attention has been devoted in various novel constraints like critical scoring criterion number, flash temperature, minimum film thickness, involute interference and contact ratio. The output from various algorithms like genetic algorithm, fmincon (constrained nonlinear minimization), NSGA-II etc. are compared to generate the best result. Hence, this is a much more precise approach for obtaining practical values of the module, pinion teeth and face-width for a minimum centre distance and a maximum power transmission for any given material.

Collaborative engineering-design support system

NASA Technical Reports Server (NTRS)

Lee, Dong HO; Decker, D. Richard

1994-01-01

Designing engineering objects requires many engineers' knowledge from different domains. There needs to be cooperative work among engineering designers to complete a design. Revisions of a design are time consuming, especially if designers work at a distance and with different design description formats. In order to reduce the design cycle, there needs to be a sharable design describing the engineering community, which can be electronically transportable. Design is a process of integrating that is not easy to define definitively. This paper presents Design Script which is a generic engineering design knowledge representation scheme that can be applied in any engineering domain. The Design Script is developed through encapsulation of common design activities and basic design components based on problem decomposition. It is implemented using CLIPS with a Windows NT graphical user interface. The physical relationships between engineering objects and their subparts can be constructed in a hierarchical manner. The same design process is repeatedly applied at each given level of hierarchy and recursively into lower levels of the hierarchy. Each class of the structure can be represented using the Design Script.

From a distance: Implications of spontaneous self-distancing for adaptive self-reflection

PubMed Central

Ayduk, Özlem; Kross, Ethan

2010-01-01

Although recent work experimental work indicates that self-distancing facilitates adaptive self-reflection, it remains unclear (a) whether spontaneously self-distancing leads to similar adaptive outcomes, (b) how spontaneous self-distancing relates to avoidance, and (c) how this strategy impacts interpersonal behavior. Three studies examined these issues demonstrating that the more participants spontaneously self-distanced while reflecting on negative memories, the less emotional (Studies 1–3) and cardiovascular (Study 2) reactivity they displayed in the short-term. Spontaneous self-distancing was also associated with lower emotional reactivity and intrusive ideation over time (Study 1). The negative association between spontaneous self-distancing and emotional reactivity was mediated by how participants construed their experience (i.e., less recounting relative to reconstruing) rather than avoidance (Studies 1–2). In addition, spontaneous self-distancing was associated with more problem-solving behavior and less reciprocation of negativity during conflicts among couples in ongoing relationships (Study 3). Although spontaneous self-distancing was empirically related to trait rumination, it explained unique variance in predicting key outcomes. PMID:20438226

High-speed 3D surface measurement with a fringe projection based optical sensor

NASA Astrophysics Data System (ADS)

Bräuer-Burchardt, Christian; Heist, Stefan; Kühmstedt, Peter; Notni, Gunther

2014-05-01

A new optical sensor based on fringe projection technique for the accurate and fast measurement of the surface of objects mainly for industrial inspection tasks is introduced. High-speed fringe projection and image recording with 180 Hz allows 3D rates up to 60 Hz. The high measurement velocity was achieved by consequent fringe code reduction and parallel data processing. Reduction of the image sequence length was obtained by omission of the Gray-code sequence by using the geometric restrictions of the measurement objects. The sensor realizes three different measurement fields between 20 x 20 mm2 and 40 x 40 mm2 with lateral spatial solutions between 10 μm and 20 μm with the same working distance. Measurement object height extension is between +/- 0.5 mm and +/- 2 mm. Height resolution between 1 μm and 5 μm can be achieved depending on the properties of the measurement objects. The sensor may be used e.g. for quality inspection of conductor boards or plugs in real-time industrial applications.

Using Model Point Spread Functions to Identifying Binary Brown Dwarf Systems

NASA Astrophysics Data System (ADS)

Matt, Kyle; Stephens, Denise C.; Lunsford, Leanne T.

2017-01-01

A Brown Dwarf (BD) is a celestial object that is not massive enough to undergo hydrogen fusion in its core. BDs can form in pairs called binaries. Due to the great distances between Earth and these BDs, they act as point sources of light and the angular separation between binary BDs can be small enough to appear as a single, unresolved object in images, according to Rayleigh Criterion. It is not currently possible to resolve some of these objects into separate light sources. Stephens and Noll (2006) developed a method that used model point spread functions (PSFs) to identify binary Trans-Neptunian Objects, we will use this method to identify binary BD systems in the Hubble Space Telescope archive. This method works by comparing model PSFs of single and binary sources to the observed PSFs. We also use a method to compare model spectral data for single and binary fits to determine the best parameter values for each component of the system. We describe these methods, its challenges and other possible uses in this poster.

A resolution measure for three-dimensional microscopy

PubMed Central

Chao, Jerry; Ram, Sripad; Abraham, Anish V.; Ward, E. Sally; Ober, Raimund J.

2009-01-01

A three-dimensional (3D) resolution measure for the conventional optical microscope is introduced which overcomes the drawbacks of the classical 3D (axial) resolution limit. Formulated within the context of a parameter estimation problem and based on the Cramer-Rao lower bound, this 3D resolution measure indicates the accuracy with which a given distance between two objects in 3D space can be determined from the acquired image. It predicts that, given enough photons from the objects of interest, arbitrarily small distances of separation can be estimated with prespecified accuracy. Using simulated images of point source pairs, we show that the maximum likelihood estimator is capable of attaining the accuracy predicted by the resolution measure. We also demonstrate how different factors, such as extraneous noise sources and the spatial orientation of the imaged object pair, can affect the accuracy with which a given distance of separation can be determined. PMID:20161040

Mental Representations Formed From Educational Website Formats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizabeth T. Cady; Kimberly R. Raddatz; Tuan Q. Tran

2006-10-01

The increasing popularity of web-based distance education places high demand on distance educators to format web pages to facilitate learning. However, limited guidelines exist regarding appropriate writing styles for web-based distance education. This study investigated the effect of four different writing styles on reader’s mental representation of hypertext. Participants studied hypertext written in one of four web-writing styles (e.g., concise, scannable, objective, and combined) and were then administered a cued association task intended to measure their mental representations of the hypertext. It is hypothesized that the scannable and combined styles will bias readers to scan rather than elaborately read, whichmore » may result in less dense mental representations (as identified through Pathfinder analysis) relative to the objective and concise writing styles. Further, the use of more descriptors in the objective writing style will lead to better integration of ideas and more dense mental representations than the concise writing style.« less

Biomechanical models for radial distance determination by the rat vibrissal system.

PubMed

Birdwell, J Alexander; Solomon, Joseph H; Thajchayapong, Montakan; Taylor, Michael A; Cheely, Matthew; Towal, R Blythe; Conradt, Jorg; Hartmann, Mitra J Z

2007-10-01

Rats use active, rhythmic movements of their whiskers to acquire tactile information about three-dimensional object features. There are no receptors along the length of the whisker; therefore all tactile information must be mechanically transduced back to receptors at the whisker base. This raises the question: how might the rat determine the radial contact position of an object along the whisker? We developed two complementary biomechanical models that show that the rat could determine radial object distance by monitoring the rate of change of moment (or equivalently, the rate of change of curvature) at the whisker base. The first model is used to explore the effects of taper and inherent whisker curvature on whisker deformation and used to predict the shapes of real rat whiskers during deflections at different radial distances. Predicted shapes closely matched experimental measurements. The second model describes the relationship between radial object distance and the rate of change of moment at the base of a tapered, inherently curved whisker. Together, these models can account for recent recordings showing that some trigeminal ganglion (Vg) neurons encode closer radial distances with increased firing rates. The models also suggest that four and only four physical variables at the whisker base -- angular position, angular velocity, moment, and rate of change of moment -- are needed to describe the dynamic state of a whisker. We interpret these results in the context of our evolving hypothesis that neural responses in Vg can be represented using a state-encoding scheme that includes combinations of these four variables.

Joint T1 and brain fiber log-demons registration using currents to model geometry.

PubMed

Siless, Viviana; Glaunès, Joan; Guevara, Pamela; Mangin, Jean-François; Poupon, Cyril; Le Bihan, Denis; Thirion, Bertrand; Fillard, Pierre

2012-01-01

We present an extension of the diffeomorphic Geometric Demons algorithm which combines the iconic registration with geometric constraints. Our algorithm works in the log-domain space, so that one can efficiently compute the deformation field of the geometry. We represent the shape of objects of interest in the space of currents which is sensitive to both location and geometric structure of objects. Currents provides a distance between geometric structures that can be defined without specifying explicit point-to-point correspondences. We demonstrate this framework by registering simultaneously T1 images and 65 fiber bundles consistently extracted in 12 subjects and compare it against non-linear T1, tensor, and multi-modal T1 + Fractional Anisotropy (FA) registration algorithms. Results show the superiority of the Log-domain Geometric Demons over their purely iconic counterparts.

An economic approach to environmental indices

EPA Science Inventory

This study uses the directional output distance function from economic productivity theory as an alternative approach to environmental index construction. We use the directional output distance function to aggregate multiple environmental objectives into one measure of environme...

Search for Near-Earth Objects with Small Aphelion Distances

NASA Technical Reports Server (NTRS)

Tholen, David J.

2004-01-01

Progress for the period 13 July 2003 through 11 August 2004 is reported. Report topics include personnel, NEO follow-up astrometry, and the continued search for near-Earth asteroids with small aphelion distances.

Effect of accelerated global expansion on the bending of light

NASA Astrophysics Data System (ADS)

Aghili, Mir Emad; Bolen, Brett; Bombelli, Luca

2017-01-01

In 2007 Rindler and Ishak showed that, contrary to previous claims, the value of the cosmological constant does have an effect on light deflection by a gravitating object in an expanding universe. In their work they considered a Schwarzschild-de Sitter (SdS) spacetime, which has a constant asymptotic expansion rate H_0. A model with a time-dependent H( t) was studied by Kantowski et al., who consider in their 2010 paper a "Swiss-cheese" model of a Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime with an embedded SdS bubble. In this paper, we generalize the Rindler and Ishak model to time-varying H( t) in another way, by considering light bending in a McVittie metric representing a gravitating object in a FLRW cosmological background. We carry out numerical simulations of the propagation of null geodesics in different McVittie spacetimes, in which we keep the values of the distances from the observer to the lensing object and to the source fixed, and vary the form of H( t).

Super-resolved microsphere-assisted Mirau digital holography by oblique illumination

NASA Astrophysics Data System (ADS)

Abbasian, Vahid; Ganjkhani, Yasaman; Akhlaghi, Ehsan A.; Anand, Arun; Javidi, Bahram; Moradi, Ali-Reza

2018-06-01

In this paper, oblique illumination is used to improve the lateral resolution and edge sharpness in microsphere (MS)-assisted Mirau digital holographic microscopy (Mirau-DHM). Abbe showed that tilting the illumination light allows entrance of higher spatial frequencies into the imaging system thus increasing the resolution power. We extended the idea to common-path DHM, based on Mirau objective, toward super-resolved 3D imaging. High magnification Mirau objectives are very expensive and low-magnification ones suffer from low resolution, therefore, any attempt to increase the effective resolution of the system may be of a great interest. We have already demonstrated the effective resolution increasing of a Mirau-DHM system by incorporating a transparent MS within the working distance of the objective. Here, we show that by integrating a MS-assisted Mirau-DHM with the oblique illumination even higher resolutions can be achieved. We have applied the technique for various samples and have shown the increase in the lateral resolution for the both cases of Mirau-DHM with and without the MS.

30 CFR 585.543 - Example of how the inverse distance formula works.

Code of Federal Regulations, 2014 CFR

2014-07-01

... works. 585.543 Section 585.543 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY AND ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER CONTINENTAL SHELF... inverse distance formula works. (a) Assume that the geographic center of the project area lies 12 miles...

30 CFR 585.543 - Example of how the inverse distance formula works.

Code of Federal Regulations, 2013 CFR

2013-07-01

... works. 585.543 Section 585.543 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY AND ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER CONTINENTAL SHELF... inverse distance formula works. (a) Assume that the geographic center of the project area lies 12 miles...

30 CFR 585.543 - Example of how the inverse distance formula works.

Code of Federal Regulations, 2012 CFR

2012-07-01

... works. 585.543 Section 585.543 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE RENEWABLE ENERGY AND ALTERNATE USES OF EXISTING FACILITIES ON THE OUTER CONTINENTAL SHELF... inverse distance formula works. (a) Assume that the geographic center of the project area lies 12 miles...

Depth perception camera for autonomous vehicle applications

NASA Astrophysics Data System (ADS)

Kornreich, Philipp

2013-05-01

An imager that can measure the distance from each pixel to the point on the object that is in focus at the pixel is described. Since it provides numeric information of the distance from the camera to all points in its field of view it is ideally suited for autonomous vehicle navigation and robotic vision. This eliminates the LIDAR conventionally used for range measurements. The light arriving at a pixel through a convex lens adds constructively only if it comes from the object point in focus at this pixel. The light from all other object points cancels. Thus, the lens selects the point on the object who's range is to be determined. The range measurement is accomplished by short light guides at each pixel. The light guides contain a p - n junction and a pair of contacts along its length. They, too, contain light sensing elements along the length. The device uses ambient light that is only coherent in spherical shell shaped light packets of thickness of one coherence length. Each of the frequency components of the broad band light arriving at a pixel has a phase proportional to the distance from an object point to its image pixel.

Defying Food - How Distance Determines Monkeys' Ability to Inhibit Reaching for Food.

PubMed

Junghans, Astrid F; Sterck, Elisabeth H M; Overduin de Vries, Anne; Evers, Catharine; De Ridder, Denise T D

2016-01-01

Objects, such as food, in the environment automatically activate and facilitate affordances, the possibilities for motoric movements in interaction with the objects. Previous research has shown that affordance activation is contingent upon the distance of the object with only proximal objects activating potential movements. However, the effect of affordance-activating proximal objects on the ability to inhibit movements has been unaddressed. The current study addressed this question with two experiments on long-tailed macaques. In both experiments monkeys were situated behind a Plexiglass screen that prevented direct access to food placed right behind the screen. The food could only be reached via a detour through one of two holes on the sides of the screen. It was assessed whether monkeys' ability to inhibit the unsuccessful immediate reaching movement forward toward the food depended on the distance at which the food was presented. Results of both Experiments revealed that monkeys reached for the proximally positioned food significantly more than for the distally positioned food, despite this Plexiglass screen preventing successful obtainment of the food. The findings reveal the effect of proximal, affordance-activating objects on the ability to resist movements involved in interacting with the objects. Implications for humans, living in environments in which proximal, or accessible food is constantly available are discussed. The findings can contribute to an understanding of why resisting accessible food in the environment is often unsuccessful.

Development of an inverse distance weighted active infrared stealth scheme using the repulsive particle swarm optimization algorithm.

PubMed

Han, Kuk-Il; Kim, Do-Hwi; Choi, Jun-Hyuk; Kim, Tae-Kuk

2018-04-20

Treatments for detection by infrared (IR) signals are higher than for other signals such as radar or sonar because an object detected by the IR sensor cannot easily recognize its detection status. Recently, research for actively reducing IR signal has been conducted to control the IR signal by adjusting the surface temperature of the object. In this paper, we propose an active IR stealth algorithm to synchronize IR signals from the object and the background around the object. The proposed method includes the repulsive particle swarm optimization statistical optimization algorithm to estimate the IR stealth surface temperature, which will result in a synchronization between the IR signals from the object and the surrounding background by setting the inverse distance weighted contrast radiant intensity (CRI) equal to zero. We tested the IR stealth performance in mid wavelength infrared (MWIR) and long wavelength infrared (LWIR) bands for a test plate located at three different positions on a forest scene to verify the proposed method. Our results show that the inverse distance weighted active IR stealth technique proposed in this study is proved to be an effective method for reducing the contrast radiant intensity between the object and background up to 32% as compared to the previous method using the CRI determined as the simple signal difference between the object and the background.

Apparent size contrasts of retinal images and size constancy as determinants of the moon illusion.

PubMed

Smith, O W; Smith, P C; Geist, C C; Zimmermann, R R

1978-06-01

Kaufman and Rock (1962) and Rock and Kaufman (1962) concluded that the moon illusion is a function of and attributable to apparent distance. They also reported a large framing effect as an exception. Analysis of the effect suggests two components which can account for the illusion independently of apparent distance. These are apparent size contrasts of visual images of discriminable features or objects of the earth with the moon's image and size constancy of the features or objects plus the interactions of the two. Apparent distances to horizons are always a consequence of the necessary conditions for the illusion. They are related to the illusion but are not a determinant of it.

Contextual Interactions in Grating Plaid Configurations Are Explained by Natural Image Statistics and Neural Modeling

PubMed Central

Ernst, Udo A.; Schiffer, Alina; Persike, Malte; Meinhardt, Günter

2016-01-01

Processing natural scenes requires the visual system to integrate local features into global object descriptions. To achieve coherent representations, the human brain uses statistical dependencies to guide weighting of local feature conjunctions. Pairwise interactions among feature detectors in early visual areas may form the early substrate of these local feature bindings. To investigate local interaction structures in visual cortex, we combined psychophysical experiments with computational modeling and natural scene analysis. We first measured contrast thresholds for 2 × 2 grating patch arrangements (plaids), which differed in spatial frequency composition (low, high, or mixed), number of grating patch co-alignments (0, 1, or 2), and inter-patch distances (1° and 2° of visual angle). Contrast thresholds for the different configurations were compared to the prediction of probability summation (PS) among detector families tuned to the four retinal positions. For 1° distance the thresholds for all configurations were larger than predicted by PS, indicating inhibitory interactions. For 2° distance, thresholds were significantly lower compared to PS when the plaids were homogeneous in spatial frequency and orientation, but not when spatial frequencies were mixed or there was at least one misalignment. Next, we constructed a neural population model with horizontal laminar structure, which reproduced the detection thresholds after adaptation of connection weights. Consistent with prior work, contextual interactions were medium-range inhibition and long-range, orientation-specific excitation. However, inclusion of orientation-specific, inhibitory interactions between populations with different spatial frequency preferences were crucial for explaining detection thresholds. Finally, for all plaid configurations we computed their likelihood of occurrence in natural images. The likelihoods turned out to be inversely related to the detection thresholds obtained at larger inter-patch distances. However, likelihoods were almost independent of inter-patch distance, implying that natural image statistics could not explain the crowding-like results at short distances. This failure of natural image statistics to resolve the patch distance modulation of plaid visibility remains a challenge to the approach. PMID:27757076

3-Dimensional Scene Perception during Active Electrolocation in a Weakly Electric Pulse Fish

PubMed Central

von der Emde, Gerhard; Behr, Katharina; Bouton, Béatrice; Engelmann, Jacob; Fetz, Steffen; Folde, Caroline

2010-01-01

Weakly electric fish use active electrolocation for object detection and orientation in their environment even in complete darkness. The African mormyrid Gnathonemus petersii can detect object parameters, such as material, size, shape, and distance. Here, we tested whether individuals of this species can learn to identify 3-dimensional objects independently of the training conditions and independently of the object's position in space (rotation-invariance; size-constancy). Individual G. petersii were trained in a two-alternative forced-choice procedure to electrically discriminate between a 3-dimensional object (S+) and several alternative objects (S−). Fish were then tested whether they could identify the S+ among novel objects and whether single components of S+ were sufficient for recognition. Size-constancy was investigated by presenting the S+ together with a larger version at different distances. Rotation-invariance was tested by rotating S+ and/or S− in 3D. Our results show that electrolocating G. petersii could (1) recognize an object independently of the S− used during training. When only single components of a complex S+ were offered, recognition of S+ was more or less affected depending on which part was used. (2) Object-size was detected independently of object distance, i.e. fish showed size-constancy. (3) The majority of the fishes tested recognized their S+ even if it was rotated in space, i.e. these fishes showed rotation-invariance. (4) Object recognition was restricted to the near field around the fish and failed when objects were moved more than about 4 cm away from the animals. Our results indicate that even in complete darkness our G. petersii were capable of complex 3-dimensional scene perception using active electrolocation. PMID:20577635

Floor Sensing System Using Laser Reflectivity for Localizing Everyday Objects and Robot

PubMed Central

Pyo, Yoonseok; Hasegawa, Tsutomu; Tsuji, Tokuo; Kurazume, Ryo; Morooka, Ken'ichi

2014-01-01

This paper describes a new method of measuring the position of everyday objects and a robot on the floor using distance and reflectance acquired by laser range finder (LRF). The information obtained by this method is important for a service robot working in a human daily life environment. Our method uses only one LRF together with a mirror installed on the wall. Moreover, since the area of sensing is limited to a LRF scanning plane parallel to the floor and just a few centimeters above the floor, the scanning covers the whole room with minimal invasion of privacy of a resident, and occlusion problem is mitigated by using mirror. We use the reflection intensity and position information obtained from the target surface. Although it is not possible to identify all objects by additionally using reflection values, it would be easier to identify unknown objects if we can eliminate easily identifiable objects by reflectance. In addition, we propose a method for measuring the robot's pose using the tag which has the encoded reflection pattern optically identified by the LRF. Our experimental results validate the effectiveness of the proposed method. PMID:24763253

Proof of principle study of the use of a CMOS active pixel sensor for proton radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seco, Joao; Depauw, Nicolas

2011-02-15

Purpose: Proof of principle study of the use of a CMOS active pixel sensor (APS) in producing proton radiographic images using the proton beam at the Massachusetts General Hospital (MGH). Methods: A CMOS APS, previously tested for use in s-ray radiation therapy applications, was used for proton beam radiographic imaging at the MGH. Two different setups were used as a proof of principle that CMOS can be used as proton imaging device: (i) a pen with two metal screws to assess spatial resolution of the CMOS and (ii) a phantom with lung tissue, bone tissue, and water to assess tissuemore » contrast of the CMOS. The sensor was then traversed by a double scattered monoenergetic proton beam at 117 MeV, and the energy deposition inside the detector was recorded to assess its energy response. Conventional x-ray images with similar setup at voltages of 70 kVp and proton images using commercial Gafchromic EBT 2 and Kodak X-Omat V films were also taken for comparison purposes. Results: Images were successfully acquired and compared to x-ray kVp and proton EBT2/X-Omat film images. The spatial resolution of the CMOS detector image is subjectively comparable to the EBT2 and Kodak X-Omat V film images obtained at the same object-detector distance. X-rays have apparent higher spatial resolution than the CMOS. However, further studies with different commercial films using proton beam irradiation demonstrate that the distance of the detector to the object is important to the amount of proton scatter contributing to the proton image. Proton images obtained with films at different distances from the source indicate that proton scatter significantly affects the CMOS image quality. Conclusion: Proton radiographic images were successfully acquired at MGH using a CMOS active pixel sensor detector. The CMOS demonstrated spatial resolution subjectively comparable to films at the same object-detector distance. Further work will be done in order to establish the spatial and energy resolution of the CMOS detector for protons. The development and use of CMOS in proton radiography could allow in vivo proton range checks, patient setup QA, and real-time tumor tracking.« less

Motivations for speeding : traffic tech.

DOT National Transportation Integrated Search

2012-10-01

Speeding reduces a drivers ability to steer safely around : curves or objects in the roadway, extends the distance necessary : to stop a vehicle, and increases the distance a vehicle travels : while the driver reacts to a dangerous situation. Spee...

The paradoxical moon illusions.

PubMed

Gilinsky, A S

1980-02-01

An adaptation theory of visual space is developed and applied to the data of a variety of studies of visual space perception. By distinguishing between the perceived distance of an object and that of the background or sky, the theory resolves the paradox of the moon illusions and relates both perceived size and perceived distance of the moon to the absolute level of spatial adaptation. The theory assumes that visual space expands or contracts in adjustment to changes in the sensory indicators of depth and provides a measure, A, of this adaptation-level. Changes in A have two effects--one on perceived size, one on perceived distance. Since A varies systematically as a function of angle of regard, availability of cues, and the total space-value, A is a measure of the moon illusions, and a practical index of individual differences by pilots and astronauts in the perception of the size and distance of objects on the ground and in the air.

Emerging Object Representations in the Visual System Predict Reaction Times for Categorization

PubMed Central

Ritchie, J. Brendan; Tovar, David A.; Carlson, Thomas A.

2015-01-01

Recognizing an object takes just a fraction of a second, less than the blink of an eye. Applying multivariate pattern analysis, or “brain decoding”, methods to magnetoencephalography (MEG) data has allowed researchers to characterize, in high temporal resolution, the emerging representation of object categories that underlie our capacity for rapid recognition. Shortly after stimulus onset, object exemplars cluster by category in a high-dimensional activation space in the brain. In this emerging activation space, the decodability of exemplar category varies over time, reflecting the brain’s transformation of visual inputs into coherent category representations. How do these emerging representations relate to categorization behavior? Recently it has been proposed that the distance of an exemplar representation from a categorical boundary in an activation space is critical for perceptual decision-making, and that reaction times should therefore correlate with distance from the boundary. The predictions of this distance hypothesis have been born out in human inferior temporal cortex (IT), an area of the brain crucial for the representation of object categories. When viewed in the context of a time varying neural signal, the optimal time to “read out” category information is when category representations in the brain are most decodable. Here, we show that the distance from a decision boundary through activation space, as measured using MEG decoding methods, correlates with reaction times for visual categorization during the period of peak decodability. Our results suggest that the brain begins to read out information about exemplar category at the optimal time for use in choice behaviour, and support the hypothesis that the structure of the representation for objects in the visual system is partially constitutive of the decision process in recognition. PMID:26107634

Individual Objective and Subjective Fixation Disparity in Near Vision

PubMed Central

Jaschinski, Wolfgang

2017-01-01

Binocular vision refers to the integration of images in the two eyes for improved visual performance and depth perception. One aspect of binocular vision is the fixation disparity, which is a suboptimal condition in individuals with respect to binocular eye movement control and subsequent neural processing. The objective fixation disparity refers to the vergence angle between the visual axes, which is measured with eye trackers. Subjective fixation disparity is tested with two monocular nonius lines which indicate the physical nonius separation required for perceived alignment. Subjective and objective fixation disparity represent the different physiological mechanisms of motor and sensory fusion, but the precise relation between these two is still unclear. This study measures both types of fixation disparity at viewing distances of 40, 30, and 24 cm while observers fixated a central stationary fusion target. 20 young adult subjects with normal binocular vision were tested repeatedly to investigate individual differences. For heterophoria and subjective fixation disparity, this study replicated that the binocular system does not properly adjust to near targets: outward (exo) deviations typically increase as the viewing distance is shortened. This exo proximity effect—however—was not found for objective fixation disparity, which–on the average–was zero. But individuals can have reliable outward (exo) or inward (eso) vergence errors. Cases with eso objective fixation disparity tend to have less exo states of subjective fixation disparity and heterophoria. In summary, the two types of fixation disparity seem to respond in a different way when the viewing distance is shortened. Motor and sensory fusion–as reflected by objective and subjective fixation disparity–exhibit complex interactions that may differ between individuals (eso versus exo) and vary with viewing distance (far versus near vision). PMID:28135308

The effect of external non-driving factors, payment type and waiting and queuing on fatigue in long distance trucking.

PubMed

Williamson, Ann; Friswell, Rena

2013-09-01

The aim of this study was to explore the effects of external influences on long distance trucking, in particular, incentive-based remuneration systems and the need to wait or queue to load or unload on driver experiences of fatigue. Long distance truck drivers (n=475) were recruited at truck rest stops on the major transport corridors within New South Wales, Australia and asked to complete a survey by self-administration or interview. The survey covered demographics, usual working arrangements, details of the last trip and safety outcomes including fatigue experiences. On average drivers' last trip was over 2000 km and took 21.5 h to complete with an additional 6h of non-driving work. Incentive payments were associated with longer working hours, greater distances driven and higher fatigue for more drivers. Drivers required to wait in queues did significantly more non-driving work and experienced fatigue more often than those who did not. Drivers who were not paid to wait did the longest trips with average weekly hours above the legal working hours limits, had the highest levels of fatigue and the highest levels of interference by work with family life. In contrast, drivers who were paid to wait did significantly less work with shorter usual hours and shorter last trips. Multivariate analysis showed that incentive-based payment and unpaid waiting in queues were significant predictors of driver fatigue. The findings suggest that mandating payment of drivers for non-driving work including waiting would reduce the amount of non-driving work required for drivers and reduce weekly hours of work. In turn this would reduce driver fatigue and safety risk as well as enhancing the efficiency of the long distance road transport industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Analysis of signals under compositional noise with applications to SONAR data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, J. Derek; Wu, Wei; Srivastava, Anuj

2013-07-09

In this paper, we consider the problem of denoising and classification of SONAR signals observed under compositional noise, i.e., they have been warped randomly along the x-axis. The traditional techniques do not account for such noise and, consequently, cannot provide a robust classification of signals. We apply a recent framework that: 1) uses a distance-based objective function for data alignment and noise reduction; and 2) leads to warping-invariant distances between signals for robust clustering and classification. We use this framework to introduce two distances that can be used for signal classification: a) a y-distance, which is the distance between themore » aligned signals; and b) an x-distance that measures the amount of warping needed to align the signals. We focus on the task of clustering and classifying objects, using acoustic spectrum (acoustic color), which is complicated by the uncertainties in aspect angles at data collections. Small changes in the aspect angles corrupt signals in a way that amounts to compositional noise. As a result, we demonstrate the use of the developed metrics in classification of acoustic color data and highlight improvements in signal classification over current methods.« less

Comparing Methods to Assess Intraobserver Measurement Error of 3D Craniofacial Landmarks Using Geometric Morphometrics Through a Digitizer Arm.

PubMed

Menéndez, Lumila Paula

2017-05-01

Intraobserver error (INTRA-OE) is the difference between repeated measurements of the same variable made by the same observer. The objective of this work was to evaluate INTRA-OE from 3D landmarks registered with a Microscribe, in different datasets: (A) the 3D coordinates, (B) linear measurements calculated from A, and (C) the six-first principal component axes. INTRA-OE was analyzed by digitizing 42 landmarks from 23 skulls in three events two weeks apart from each other. Systematic error was tested through repeated measures ANOVA (ANOVA-RM), while random error through intraclass correlation coefficient. Results showed that the largest differences between the three observations were found in the first dataset. Some anatomical points like nasion, ectoconchion, temporosphenoparietal, asterion, and temporomandibular presented the highest INTRA-OE. In the second dataset, local distances had higher INTRA-OE than global distances while the third dataset showed the lowest INTRA-OE. © 2016 American Academy of Forensic Sciences.

Autofocusing Airy beam STED microscopy with long focal distance

NASA Astrophysics Data System (ADS)

Hu, Di; Liang, Yao; Chen, Yin; Chen, Zan Hui; Huang, Xu Guang

2017-12-01

Stimulated emission depletion (STED) is a very important technique in super-resolution microscopy. Until now, while autofocusing Airy beam (AAB) has been an attractive theme for both theoretical and applied researches, there are almost no report on AABs being used in STED microscopy. In this paper, we propose a novel STED microscopy based on AABs. A radially symmetric 3/2 phase plate is involved to simultaneously generate autofocusing excitation- and depletion-Airy beams. Remarkably, the AAB can auto-focus to a wavelength-scale spot with a long focal depth (several millimeters): on the contrary, the working distance of a conventional high numerical aperture (NA) objective is usually very short (about 200 μm). Our calculations indicate that the AAB based STED microscopy can achieve a super-resolution spot with FWHM of 58 nm while the focal length is 4.638 mm. Moreover, with properties of non-diffracting and self-healing, the Airy beam could enable a reduction of the scattering distortion induced by the specimens and has a great potential in imaging thick specimens.

Are the Dyson rings around pulsars detectable?

NASA Astrophysics Data System (ADS)

Osmanov, Z.

2018-04-01

In the previous paper ring (Osmanov 2016) (henceforth Paper-I) we have extended the idea of Freeman Dyson and have shown that a supercivilization has to use ring-like megastructures around pulsars instead of a spherical shell. In this work we reexamine the same problem in the observational context and we show that facilities of modern infrared (IR) telescopes (Very Large Telescope Interferometer and Wide-field Infrared Survey Explorer (WISE)) might efficiently monitor the nearby zone of the solar system and search for the IR Dyson-rings up to distances of the order of 0.2 kpc, corresponding to the current highest achievable angular resolution, 0.001 mas. In this case the total number of pulsars in the observationally reachable area is about 64 +/- 21. We show that pulsars from the distance of the order of ~ 1 kpc are still visible for WISE as point-like sources but in order to confirm that the object is the neutron star, one has to use the ultraviolet telescopes, which at this moment cannot provide enough sensitivity.

A study of the sink effect by blood vessels in radiofrequency ablation.

PubMed

Zorbas, George; Samaras, Theodoros

2015-02-01

The objective of the current work was to study the sink effect in radiofrequency ablation (RFA) caused by a blood vessel located close to an electrode in a two-compartment numerical model, consisting of a spherical tumor embedded in healthy liver tissue. Several blood vessels of different sizes were studied at different distances from the electrode. It was found that when a straight blood vessel, cylindrical in shape, is located parallel to the electrode, the minimum distance for a drop of only 10% in the isothermal treatment volume above 50°C, compared to the model without the blood vessel, varies from 4.49 mm (for a vessel of 2mm in diameter) to 20.02 mm (for a vessel 20mm in diameter). The results can be used as a guideline to clinical practitioners, in order to quickly assess the potential impact of existing blood vessels on the resulting treatment volume. Copyright © 2014 Elsevier Ltd. All rights reserved.

Judgements about the relation between force and trajectory variables in verbally described ballistic projectile motion.

PubMed

White, Peter A

2013-01-01

How accurate are explicit judgements about familiar forms of object motion, and how are they made? Participants judged the relations between force exerted in kicking a soccer ball and variables that define the trajectory of the ball: launch angle, maximum height attained, and maximum distance reached. Judgements tended to conform to a simple heuristic that judged force tends to increase as maximum height and maximum distance increase, with launch angle not being influential. Support was also found for the converse prediction, that judged maximum height and distance tend to increase as the amount of force described in the kick increases. The observed judgemental tendencies did not resemble the objective relations, in which force is a function of interactions between the trajectory variables. This adds to a body of research indicating that practical knowledge based on experiences of actions on objects is not available to the processes that generate judgements in higher cognition and that such judgements are generated by simple rules that do not capture the objective interactions between the physical variables.

Directional Radio-Frequency Identification Tag Reader

NASA Technical Reports Server (NTRS)

Medelius, Pedro J.; Taylor, John D.; Henderson, John J.

2004-01-01

A directional radio-frequency identification (RFID) tag reader has been designed to facilitate finding a specific object among many objects in a crowded room. The device could be an adjunct to an electronic inventory system that tracks RFID-tagged objects as they move through reader-equipped doorways. Whereas commercial RFID-tag readers do not measure directions to tagged objects, the device is equipped with a phased-array antenna and a received signal-strength indicator (RSSI) circuit for measuring direction. At the beginning of operation, it is set to address only the RFID tag of interest. It then continuously transmits a signal to interrogate that tag while varying the radiation pattern of the antenna. It identifies the direction to the tag as the radiation pattern direction of peak strength of the signal returned by the tag. An approximate distance to the tag is calculated from the peak signal strength. The direction and distance can be displayed on a screen. A prototype containing a Yagi antenna was found to be capable of detecting a 915.5-MHz tag at a distance of approximately equal to 15 ft (approximately equal to 4.6 m).

Orientation Control Method and System for Object in Motion

NASA Technical Reports Server (NTRS)

Whorton, Mark Stephen (Inventor); Redmon, Jr., John W. (Inventor); Cox, Mark D. (Inventor)

2012-01-01

An object in motion has a force applied thereto at a point of application. By moving the point of application such that the distance between the object's center-of-mass and the point of application is changed, the object's orientation can be changed/adjusted.

Fire Protection Informational Exchange

DTIC Science & Technology

2016-07-01

0.95 L/min concurrent spray & 274x521 mm pool (66°C) i. Persistent fuels; turbine fuel in spray/pool; lubricant, hydraulic fluid in spray ii...conjugate image plane La Vision sCMOS + Kl long- distance microscope with CF4 objective wire .. " " " " ... in-line hologram image plane La...distance microscope with CF4 objective wire I phase disrurbanc.e (f= 2000 nun) .. " " " " ... in-line hologram image plane La Vision sCNlOS

Emmert's Law and the moon illusion.

PubMed

Gregory, Richard L

2008-01-01

A cognitive account is offered of puzzling, though well known phenomena, including increased size of afterimages with greater distance (Emmert's Law) and increased size of the moon near the horizon (the Moon Illusion). Various classical distortion illusions are explained by Size Scaling when inappropriate to distance, 'flipping' depth ambiguity being used to separate botton-up and top-down visual scaling. Helmholtz's general Principle is discussed with simpler wording - that retinal images are attributed to objects - for object recognition and spatial vision.

A New 3D Object Pose Detection Method Using LIDAR Shape Set

PubMed Central

Kim, Jung-Un

2018-01-01

In object detection systems for autonomous driving, LIDAR sensors provide very useful information. However, problems occur because the object representation is greatly distorted by changes in distance. To solve this problem, we propose a LIDAR shape set that reconstructs the shape surrounding the object more clearly by using the LIDAR point information projected on the object. The LIDAR shape set restores object shape edges from a bird’s eye view by filtering LIDAR points projected on a 2D pixel-based front view. In this study, we use this shape set for two purposes. The first is to supplement the shape set with a LIDAR Feature map, and the second is to divide the entire shape set according to the gradient of the depth and density to create a 2D and 3D bounding box proposal for each object. We present a multimodal fusion framework that classifies objects and restores the 3D pose of each object using enhanced feature maps and shape-based proposals. The network structure consists of a VGG -based object classifier that receives multiple inputs and a LIDAR-based Region Proposal Networks (RPN) that identifies object poses. It works in a very intuitive and efficient manner and can be extended to other classes other than vehicles. Our research has outperformed object classification accuracy (Average Precision, AP) and 3D pose restoration accuracy (3D bounding box recall rate) based on the latest studies conducted with KITTI data sets. PMID:29547551

A New 3D Object Pose Detection Method Using LIDAR Shape Set.

PubMed

Kim, Jung-Un; Kang, Hang-Bong

2018-03-16

In object detection systems for autonomous driving, LIDAR sensors provide very useful information. However, problems occur because the object representation is greatly distorted by changes in distance. To solve this problem, we propose a LIDAR shape set that reconstructs the shape surrounding the object more clearly by using the LIDAR point information projected on the object. The LIDAR shape set restores object shape edges from a bird's eye view by filtering LIDAR points projected on a 2D pixel-based front view. In this study, we use this shape set for two purposes. The first is to supplement the shape set with a LIDAR Feature map, and the second is to divide the entire shape set according to the gradient of the depth and density to create a 2D and 3D bounding box proposal for each object. We present a multimodal fusion framework that classifies objects and restores the 3D pose of each object using enhanced feature maps and shape-based proposals. The network structure consists of a VGG -based object classifier that receives multiple inputs and a LIDAR-based Region Proposal Networks (RPN) that identifies object poses. It works in a very intuitive and efficient manner and can be extended to other classes other than vehicles. Our research has outperformed object classification accuracy (Average Precision, AP) and 3D pose restoration accuracy (3D bounding box recall rate) based on the latest studies conducted with KITTI data sets.

Displacement, distance, and shape measurements of fast-rotating rough objects by two mutually tilted interference fringe systems.

PubMed

Günther, Philipp; Kuschmierz, Robert; Pfister, Thorsten; Czarske, Jürgen W

2013-05-01

The precise distance measurement of fast-moving rough surfaces is important in several applications such as lathe monitoring. A nonincremental interferometer based on two mutually tilted interference fringe systems has been realized for this task. The distance is coded in the phase difference between the generated interference signals corresponding to the fringe systems. Large tilting angles between the interference fringe systems are necessary for a high sensitivity. However, due to the speckle effect at rough surfaces, different envelopes and phase jumps of the interference signals occur. At large tilting angles, these signals become dissimilar, resulting in a small correlation coefficient and a high measurement uncertainty. Based on a matching of illumination and receiving optics, the correlation coefficient and the phase difference estimation have been improved significantly. For axial displacement measurements of recurring rough surfaces, laterally moving with velocities of 5 m/s, an uncertainty of 110 nm has been attained. For nonrecurring surfaces, a distance measurement uncertainty of 830 nm has been achieved. Incorporating the additionally measured lateral velocity and the rotational speed, the two-dimensional shape of rotating objects results. Since the measurement uncertainty of the displacement, distance, and shape is nearly independent of the lateral surface velocity, this technique is predestined for fast-rotating objects, such as crankshafts, camshafts, vacuum pump shafts, or turning parts of lathes.

Object-based change detection method using refined Markov random field

NASA Astrophysics Data System (ADS)

Peng, Daifeng; Zhang, Yongjun

2017-01-01

In order to fully consider the local spatial constraints between neighboring objects in object-based change detection (OBCD), an OBCD approach is presented by introducing a refined Markov random field (MRF). First, two periods of images are stacked and segmented to produce image objects. Second, object spectral and textual histogram features are extracted and G-statistic is implemented to measure the distance among different histogram distributions. Meanwhile, object heterogeneity is calculated by combining spectral and textual histogram distance using adaptive weight. Third, an expectation-maximization algorithm is applied for determining the change category of each object and the initial change map is then generated. Finally, a refined change map is produced by employing the proposed refined object-based MRF method. Three experiments were conducted and compared with some state-of-the-art unsupervised OBCD methods to evaluate the effectiveness of the proposed method. Experimental results demonstrate that the proposed method obtains the highest accuracy among the methods used in this paper, which confirms its validness and effectiveness in OBCD.

DDM at Work. Reply to comments on "Dependency distance: A new perspective on syntactic patterns in natural languages"

NASA Astrophysics Data System (ADS)

Xu, Chunshan; Liang, Junying; Liu, Haitao

2017-07-01

We provide responses to the commentaries in this volume to evaluate, clarify and extend some of the arguments in Dependency distance: A new perspective on syntactic patterns in natural languages. Evidences show that DDM (dependency distance minimization) is an important linguistic universal, biologically or cognitively motivated, in shaping the language system. As a general tendency, DDM works quite well in theoretical argumentations as well as practical applications. However, this does not mean that DDM is the only linguistic universal that works: it is highly possible that other factors, which might be biologically, physically, socially or culturally motivated, work as well to jointly mold languages.

Wide-Field Infrared Survey Explorer Observations of Young Stellar Objects in the Lynds 1509 Dark Cloud in Auriga

NASA Technical Reports Server (NTRS)

Liu, Wilson M.; Padgett, Deborah L.; Terebey, Susan; Angione, John; Rebull, Luisa M.; McCollum, Bruce; Fajardo-Acosta, Sergio; Leisawitz, David

2015-01-01

The Wide-Field Infrared Survey Explorer (WISE) has uncovered a striking cluster of young stellar object (YSO) candidates associated with the L1509 dark cloud in Auriga. The WISE observations, at 3.4, 4.6, 12, and 22 microns, show a number of objects with colors consistent with YSOs, and their spectral energy distributions suggest the presence of circumstellar dust emission, including numerous Class I, flat spectrum, and Class II objects. In general, the YSOs in L1509 are much more tightly clustered than YSOs in other dark clouds in the Taurus-Auriga star forming region, with Class I and flat spectrum objects confined to the densest aggregates, and Class II objects more sparsely distributed. We estimate a most probable distance of 485-700 pc, and possibly as far as the previously estimated distance of 2 kpc.

Reconstruction methods for phase-contrast tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raven, C.

Phase contrast imaging with coherent x-rays can be distinguished in outline imaging and holography, depending on the wavelength {lambda}, the object size d and the object-to-detector distance r. When r << d{sup 2}{lambda}, phase contrast occurs only in regions where the refractive index fastly changes, i.e. at interfaces and edges in the sample. With increasing object-to-detector distance we come in the area of holographic imaging. The image contrast outside the shadow region of the object is due to interference of the direct, undiffracted beam and a beam diffracted by the object, or, in terms of holography, the interference of amore » reference wave with the object wave. Both, outline imaging and holography, offer the possibility to obtain three dimensional information of the sample in conjunction with a tomographic technique. But the data treatment and the kind of information one can obtain from the reconstruction is different.« less

Prevalence of overestimation or underestimation of the functional capacity using MRC score as compared to 6-minute walk test in patients with cardio-respiratory disorders.

PubMed

Callens, Etienne; Graba, Sémia; Essalhi, Mohamed; Gillet-Juvin, Karine; Chevalier-Bidaud, Brigitte; Chenu, Romain; Mahut, Bruno; Delclaux, Christophe

2014-09-01

The first objective of our study was to assess whether patients diagnosed with cardio-respiratory disorders report overestimation or underestimation on recall (Medical Research Council (MRC) dyspnea scale) of their true functional capacity (walked distance during a 6-minute walk test (6MWT)). The second objective was to assess whether the measurement of breathlessness at the end of a 6MWT (Borg score) may help to identify dyspneic patients on recall. The 6MWTs of 746 patients aged from 40 to 80 years who were diagnosed with either chronic obstructive pulmonary disease (COPD, n = 355), diffuse parenchymal lung disease (n = 140), pulmonary vascular diseases (n = 188) or congestive heart failure (n = 63) were selected from a prospective Clinical Database Warehouse. The percentage of patients who overestimated (MRC ≤ 2 with distance < lower limit of normal (LLN), 61/746, 8%; 95% confidence interval (CI): 6 to 10%) or underestimated (MRC > 2 with distance ≥LLN, 121/746, 16%; 95%CI: 14 to 19%) on recall their capacity was elevated. The overestimation seemed related to self-limitation, while the underestimation seemed related to patients who "work through" their breathing discomfort. These two latter groups of patients were mainly diagnosed with COPD. A Borg dyspnea score >3 (upper limit of normal) at the end of the 6MWT had 84% specificity for the prediction of a MRC score >1. Almost one fourth of patients suffering from cardio-pulmonary disorders overestimate or underestimate on recall their true functional capacity. An elevated Borg dyspnea score at the end of the 6MWT has a good specificity to predict dyspnea on recall.

The role of material flexibility on the drying transition of water between hydrophobic objects: A thermodynamic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altabet, Y. Elia; Debenedetti, Pablo G., E-mail: pdebene@princeton.edu

2014-11-14

Liquid water confined between hydrophobic objects of sufficient size becomes metastable with respect to its vapor at separations smaller than a critical drying distance. Macroscopic thermodynamic arguments predicting this distance have been restricted to the limit of perfectly rigid confining materials. However, no material is perfectly rigid and it is of interest to account for this fact in the thermodynamic analysis. We present a theory that combines the current macroscopic theory with the thermodynamics of elasticity to derive an expression for the critical drying distance for liquids confined between flexible materials. The resulting expression is the sum of the well-knownmore » drying distance for perfectly rigid confining materials and a new term that accounts for flexibility. Thermodynamic arguments show that this new term is necessarily positive, meaning that flexibility increases the critical drying distance. To study the expected magnitude and scaling behavior of the flexible term, we consider the specific case of water and present an example of drying between thin square elastic plates that are simply supported along two opposite edges and free at the remaining two. We find that the flexible term can be the same order of magnitude or greater than the rigid solution for materials of biological interest at ambient conditions. In addition, we find that when the rigid solution scales with the characteristic size of the immersed objects, the flexible term is independent of size and vice versa. Thus, the scaling behavior of the overall drying distance will depend on the relative weights of the rigid and flexible contributions.« less

Spatial analyses for nonoverlapping objects with size variations and their application to coral communities.

PubMed

Muko, Soyoka; Shimatani, Ichiro K; Nozawa, Yoko

2014-07-01

Spatial distributions of individuals are conventionally analysed by representing objects as dimensionless points, in which spatial statistics are based on centre-to-centre distances. However, if organisms expand without overlapping and show size variations, such as is the case for encrusting corals, interobject spacing is crucial for spatial associations where interactions occur. We introduced new pairwise statistics using minimum distances between objects and demonstrated their utility when examining encrusting coral community data. We also calculated the conventional point process statistics and the grid-based statistics to clarify the advantages and limitations of each spatial statistical method. For simplicity, coral colonies were approximated by disks in these demonstrations. Focusing on short-distance effects, the use of minimum distances revealed that almost all coral genera were aggregated at a scale of 1-25 cm. However, when fragmented colonies (ramets) were treated as a genet, a genet-level analysis indicated weak or no aggregation, suggesting that most corals were randomly distributed and that fragmentation was the primary cause of colony aggregations. In contrast, point process statistics showed larger aggregation scales, presumably because centre-to-centre distances included both intercolony spacing and colony sizes (radius). The grid-based statistics were able to quantify the patch (aggregation) scale of colonies, but the scale was strongly affected by the colony size. Our approach quantitatively showed repulsive effects between an aggressive genus and a competitively weak genus, while the grid-based statistics (covariance function) also showed repulsion although the spatial scale indicated from the statistics was not directly interpretable in terms of ecological meaning. The use of minimum distances together with previously proposed spatial statistics helped us to extend our understanding of the spatial patterns of nonoverlapping objects that vary in size and the associated specific scales. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

Test of the Practicality and Feasibility of EDoF-Empowered Image Sensors for Long-Range Biometrics.

PubMed

Hsieh, Sheng-Hsun; Li, Yung-Hui; Tien, Chung-Hao

2016-11-25

For many practical applications of image sensors, how to extend the depth-of-field (DoF) is an important research topic; if successfully implemented, it could be beneficial in various applications, from photography to biometrics. In this work, we want to examine the feasibility and practicability of a well-known "extended DoF" (EDoF) technique, or "wavefront coding," by building real-time long-range iris recognition and performing large-scale iris recognition. The key to the success of long-range iris recognition includes long DoF and image quality invariance toward various object distance, which is strict and harsh enough to test the practicality and feasibility of EDoF-empowered image sensors. Besides image sensor modification, we also explored the possibility of varying enrollment/testing pairs. With 512 iris images from 32 Asian people as the database, 400-mm focal length and F/6.3 optics over 3 m working distance, our results prove that a sophisticated coding design scheme plus homogeneous enrollment/testing setups can effectively overcome the blurring caused by phase modulation and omit Wiener-based restoration. In our experiments, which are based on 3328 iris images in total, the EDoF factor can achieve a result 3.71 times better than the original system without a loss of recognition accuracy.

The representation of spacetime through steep time functions

NASA Astrophysics Data System (ADS)

Minguzzi, Ettore

2018-02-01

In a recent work I showed that the family of smooth steep time functions can be used to recover the order, the topology and the (Lorentz-Finsler) distance of spacetime. In this work I present the main ideas entering the proof of the (smooth) distance formula, particularly the product trick which converts metric statements into causal ones. The paper ends with a second proof of the distance formula valid for globally hyperbolic Lorentzian spacetimes.

Comparative evaluation of ultrasound scanner accuracy in distance measurement

NASA Astrophysics Data System (ADS)

Branca, F. P.; Sciuto, S. A.; Scorza, A.

2012-10-01

The aim of the present study is to develop and compare two different automatic methods for accuracy evaluation in ultrasound phantom measurements on B-mode images: both of them give as a result the relative error e between measured distances, performed by 14 brand new ultrasound medical scanners, and nominal distances, among nylon wires embedded in a reference test object. The first method is based on a least squares estimation, while the second one applies the mean value of the same distance evaluated at different locations in ultrasound image (same distance method). Results for both of them are proposed and explained.

Measuring Distance of Fuzzy Numbers by Trapezoidal Fuzzy Numbers

NASA Astrophysics Data System (ADS)

Hajjari, Tayebeh

2010-11-01

Fuzzy numbers and more generally linguistic values are approximate assessments, given by experts and accepted by decision-makers when obtaining value that is more accurate is impossible or unnecessary. Distance between two fuzzy numbers plays an important role in linguistic decision-making. It is reasonable to define a fuzzy distance between fuzzy objects. To achieve this aim, the researcher presents a new distance measure for fuzzy numbers by means of improved centroid distance method. The metric properties are also studied. The advantage is the calculation of the proposed method is far simple than previous approaches.

Telepresence-enabled research and developing work practices

NASA Astrophysics Data System (ADS)

Mirmalek, Z.

2016-02-01

In the fall of 2014, a group of scientists and students conducted two weeks of telepresence-enabled research from the University of Rhode Island Inner Space Center and Woods Hole Oceanographic Institution with the Exploration Vessel Nautilus, which was at sea studying the Kick'em Jenny submarine volcano and Barbados Mud Volcanoes. The way that they conducted their work was not so different from other telepresence-enabled ocean science exploration. As a group, they spanned geographic distance, science expertise, exploration experience, and telepresence-enabled research experience. They were connected through technologies and work culture (e.g., shared habits, values, and practices particular to a community). Uniquely, their project included an NSF-sponsored cultural study on the workgroups' own use of technologies and social processes. The objective of the cultural study was, in part, to identify social and technical features of the work environment that present opportunities to better support science exploration via telepresence. Drawing from this case, and related research, I present some analysis on the developing work culture of telepresence-enabled research and highlight potential adjustments.

Comparison of objective refraction in darkness to cycloplegic refraction: a pilot study.

PubMed

Vasudevan, Balamurali; Ciuffreda, Kenneth J; Meehan, Kelly; Grk, Dejana; Cox, Misty

2016-03-01

The aim was to assess non-cycloplegic objective refraction in darkness using an open-field auto-refractor, and furthermore to compare it with distance cycloplegic subjective refraction and distance cycloplegic retinoscopy in the light, in children and young adults. Twenty-three, visually-normal, young-adults (46 eyes) ages 23 to 31 years, and five children (10 eyes) ages five to 12 years, participated in the study. The spherical component of their refraction ranged from -2.25 D to +3.75 D with a mean of +1.80 D, and a mean cylinder of -0.70 D. Three techniques were used to assess refractive error. An objective measure of the non-cycloplegic refractive state was obtained using an open-field autorefractor (WAM-5500) after five minutes in the dark to allow for dissipation of accommodative transients and relaxation of accommodation. In addition, both distance retinoscopy and subjective distance refraction were performed following cycloplegia (Cyclopentolate, 1%) using conventional clinical procedures. All measurements were obtained on the same day within a single session. The spherical component of the refraction was compared among the three techniques in both the children and adults. There was no significant difference in spherical refraction among the three techniques: non-cycloplegic objective refraction in the dark, distance cycloplegic retinoscopy and distance cycloplegic subjective refraction, in either the adults [F(2, 137) = 0.79, p = 0.45] or the children [F(2, 27) = 0.47, p = 0.62]. Mean difference in the spherical component between refraction in the dark and the cycloplegic distance retinoscopy was -0.34 D (r = 0.89) in the adults and +0.14 D (r = 0.96) in the children. The mean difference in spherical component between refraction in the dark and the cycloplegic distance subjective refraction was -0.25 D (r = 0.92) in the adults and -0.05 D (r = 0.95) in the children. Comparison of the spherical refractive component between the three techniques was not significantly different and furthermore, they were highly correlated in both the children and adults in this pilot study. Non-cycloplegic refraction in the dark may provide a reliable adjunct or alternative to conventional cycloplegic refraction in both children and young adults. © 2016 Optometry Australia.

A blind human expert echolocator shows size constancy for objects perceived by echoes.

PubMed

Milne, Jennifer L; Anello, Mimma; Goodale, Melvyn A; Thaler, Lore

2015-01-01

Some blind humans make clicking noises with their mouth and use the reflected echoes to perceive objects and surfaces. This technique can operate as a crude substitute for vision, allowing human echolocators to perceive silent, distal objects. Here, we tested if echolocation would, like vision, show size constancy. To investigate this, we asked a blind expert echolocator (EE) to echolocate objects of different physical sizes presented at different distances. The EE consistently identified the true physical size of the objects independent of distance. In contrast, blind and blindfolded sighted controls did not show size constancy, even when encouraged to use mouth clicks, claps, or other signals. These findings suggest that size constancy is not a purely visual phenomenon, but that it can operate via an auditory-based substitute for vision, such as human echolocation.

Inclusive Approach to the Psycho-Pedagogical Assistance of Distance Learning

ERIC Educational Resources Information Center

Akhmetova, Daniya Z.

2014-01-01

Author focuses on three groups of problems: quality of distance learning and e-learning; necessity to develop the facilitation skills for teachers who work using distance learning technologies; realization of inclusive approach for the organization of distance learning in inclusive groups where people with disabilities study with people without…

Extracting contours of oval-shaped objects by Hough transform and minimal path algorithms

NASA Astrophysics Data System (ADS)

Tleis, Mohamed; Verbeek, Fons J.

2014-04-01

Circular and oval-like objects are very common in cell and micro biology. These objects need to be analyzed, and to that end, digitized images from the microscope are used so as to come to an automated analysis pipeline. It is essential to detect all the objects in an image as well as to extract the exact contour of each individual object. In this manner it becomes possible to perform measurements on these objects, i.e. shape and texture features. Our measurement objective is achieved by probing contour detection through dynamic programming. In this paper we describe a method that uses Hough transform and two minimal path algorithms to detect contours of (ovoid-like) objects. These algorithms are based on an existing grey-weighted distance transform and a new algorithm to extract the circular shortest path in an image. The methods are tested on an artificial dataset of a 1000 images, with an F1-score of 0.972. In a case study with yeast cells, contours from our methods were compared with another solution using Pratt's figure of merit. Results indicate that our methods were more precise based on a comparison with a ground-truth dataset. As far as yeast cells are concerned, the segmentation and measurement results enable, in future work, to retrieve information from different developmental stages of the cell using complex features.

Illusory Distance Modulates Perceived Size of Afterimage despite the Disappearance of Depth Cues

PubMed Central

Liu, Shengxi; Lei, Quan

2016-01-01

It is known that the perceived size of an afterimage is modulated by the perceived distance between the observer and the depth plane on which the afterimage is projected (Emmert’s law). Illusions like Ponzo demonstrate that illusory distance induced by depth cues can also affect the perceived size of an object. In this study, we report that the illusory distance not only modulates the perceived size of object’s afterimage during the presence of the depth cues, but the modulation persists after the disappearance of the depth cues. We used an adapted version of the classic Ponzo illusion. Illusory depth perception was induced by linear perspective cues with two tilted lines converging at the upper boundary of the display. Two horizontal bars were placed between the two lines, resulting in a percept of the upper bar to be farther away than the lower bar. Observers were instructed to make judgment about the relative size of the afterimage of the lower and the upper bars after adaptation. When the perspective cues and the bars were static, the illusory effect of the Ponzo afterimage is consistent with that of the traditional size-distance illusion. When the perspective cues were flickering and the bars were static, only the afterimage of the latter was perceived, yet still a considerable amount of the illusory effect was perceived. The results could not be explained by memory of a prejudgment of the bar length during the adaptation phase. The findings suggest that cooccurrences of depth cues and object may link a depth marker for the object, so that the perceived size of the object or its afterimage is modulated by feedback of depth information from higher-level visual cortex even when there is no depth cues directly available on the retinal level. PMID:27391335

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reaugh, J. E.

HE ignition caused by shear localization is the principal concern for safety analyses of postulated mechanical insults to explosive assemblies. Although prompt detonation from shock is certainly a concern, insults that lead to prompt detonation are associated with high velocity, and correspondingly rare. For high-density HMX assemblies, an impact speed (by a steel object) of 400 m/s is needed to develop a detonation in a run distance less than 30 mm. To achieve a steady plane shock, which results in the shortest run distance to detonation for a given peak pressure, the impactor diameter must exceed 60 mm, and thicknessmore » approach 20 mm. Thinner plates and/or smaller diameter ones require even higher impact velocity. Ignitions from shear localization, however, have been observed from impacts less than 50 m/s in Steven tests, less than 30 m/s from spigot impact tests, and less than 10 m/s from various drop tests. This lower velocity range is much frequent in postulated mechanical insults. Preliminary computer simulations and analyses of a variety of such tests have suggested that although each is accompanied by shear localization, there are differing detailed mechanisms at work that cause the ignitions. We identify those mechanisms that may be at work in a variety of such tests, and suggest how models of shear ignition, such as HERMES, may be revised and calibrated to conform to experiment. We suggest combining additional experiments with computer simulations and model development to begin confirm or uncover mechanisms that may be at work in a specific postulated event.« less

Use of Information and Communication Technologies in India's First Open University: Experience and Perceptions of Learners and Learner Support Providers

ERIC Educational Resources Information Center

Satyanarayana, P.; Meduri, Emmanuel D. K.

2015-01-01

Dr. B. R. Ambedkar Open University (BRAOU), the first distance teaching university in India, was a great educational event. It started a new chapter in the history of India's distance higher education. The general objects this research studies are: (1) to identify the information and communication technologies used in open distance education…

Font size and viewing distance of handheld smart phones.

PubMed

Bababekova, Yuliya; Rosenfield, Mark; Hue, Jennifer E; Huang, Rae R

2011-07-01

The use of handheld smart phones for written communication is becoming ubiquitous in modern society. The relatively small screens found in these devices may necessitate close working distances and small text sizes, which can increase the demands placed on accommodation and vergence. Font size and viewing distance were measured while subjects used handheld electronic devices in two separate trials. In the first study (n=129), subjects were asked to show a typical text message on their own personal phone and to hold the device "as if they were about to read a text message." A second trial was conducted in a similar manner except subjects (n=100) were asked to view a specific web page from the internet. For text messages and internet viewing, the mean font size was 1.1 M (range, 0.7 to 2.1 M) and 0.8 M (range, 0.3 to 1.4 M), respectively. The mean working distance for text messages and internet viewing was 36.2 cm (range, 17.5 to 58.0 cm) and 32.2 cm (range, 19 to 60 cm), respectively. The mean font size for both conditions was comparable with newspaper print, although some subjects viewed text that was considerably smaller. However, the mean working distances were closer than the typical near working distance of 40 cm for adults when viewing hardcopy text. These close distances place increased demands on both accommodation and vergence, which could exacerbate symptoms. Practitioners need to consider the closer distances adopted while viewing material on smart phones when examining patients and prescribing refractive corrections for use at near, as well as when treating patients presenting with asthenopia associated with nearwork. Copyright © 2011 American Academy of Optometry

Surface-brightness profiles of dwarf galaxies in the NGC 5044 Group: Implications for the luminosity-shape and scalelength-shape relationships as distance indicators

NASA Astrophysics Data System (ADS)

Young, C. K.; Currie, M. J.

2001-04-01

In a recent paper, which presents CCD photometry for fifteen dwarf and intermediate early-type galaxies in the NGC 5044 Group, it has been claimed that ``a few relatively bright galaxies with ``convex'' profiles destroy the known relation between total magnitude and the ``shape'' parameter... thus ruling out the use of this relation as a distance indicator for individual galaxies''. In the same paper, further reasons were cited supposedly ``limiting also its use as a distance indicator for groups of galaxies''. We demonstrate that none of the three relatively bright galaxies cited as possessing ``convex'' profiles actually has a convex profile, and that one of these objects should be excluded because it is a late-type galaxy. Of the two remaining objects, one has an anomalous profile shape whilst the other is brighter than one might expect from its colour alone. However, we show that all of the other issues raised have already been accounted for by Young & Currie (\\cite{you94}, \\cite{you95} & \\cite{you98}). The main implications of the new observations are: (1) that the case of one galaxy with an anomalous profile shape, N42, highlights the need for some a priori criteria to be defined in order to establish objectively which objects are not suitable for distance determinations; and (2) on the basis of another unusual galaxy, N50, colour has now been shown to be a poorer discriminant between objects of the same profile shape and scalelength (but of different central surface brightness) than previously thought. How significant this latter problem is depends on how common N50-like objects are. This consideration reinforces the case for always using the more general scalelength-shape relationship of Young & Currie (\\cite{you95}) in preference to the luminosity-shape one of Young & Currie (\\cite{you94}). Reassuringly, through a re-analysis of the same CCD photometry, we find that NGC 5044 Group galaxies observe a tight scalelength-shape relationship. This finding supports the view that the scalelength-shape relationship is a viable distance indicator.

Learning Distance Functions for Exemplar-Based Object Recognition

DTIC Science & Technology

2007-08-08

requires prior specific permission. Learning Distance Functions for Exemplar-Based Object Recognition by Andrea Lynn Frome B.S. ( Mary Washington...fantastic advisor and advocate when I was at Mary Washington College i and has since become a dear friend. Thank you, Dr. Bass, for continuing to stand...Antonio Torralba. 5 Chapter 1. Introduction 0 5 10 15 20 25 30 35 10 15 20 25 30 35 40 45 50 55 60 65 70 Number of training examples per class M ea n

Learning Distance Functions for Exemplar-Based Object Recognition

DTIC Science & Technology

2007-01-01

Learning Distance Functions for Exemplar-Based Object Recognition by Andrea Lynn Frome B.S. ( Mary Washington College) 1996 A dissertation submitted...advisor and advocate when I was at Mary Washington College i and has since become a dear friend. Thank you, Dr. Bass, for continuing to stand by my...Torralba. 5 Chapter 1. Introduction 0 5 10 15 20 25 30 35 10 15 20 25 30 35 40 45 50 55 60 65 70 Number of training examples per class M ea n re co

7 CFR 1703.101 - Policy.

Code of Federal Regulations, 2014 CFR

2014-01-01

... RURAL DEVELOPMENT Distance Learning and Telemedicine Loan and Grant Program-General § 1703.101 Policy... rural Americans. To further this objective, RUS will provide financial assistance to distance learning... educational, learning, training, and health care services. (b) In providing financial assistance, RUS will...

Speeding-Related Multi-Vehicle Fatal Crashes Involving Large Trucks

DOT National Transportation Integrated Search

1999-12-01

Speeding reduces a drivers ability to steer safely around curves or objects in the roadway, extends the distance necessary to stop a vehicle, and increases the distance a vehicle travels while the driver reacts to a dangerous situation. The danger...

3D visual mechinism by neural networkings

NASA Astrophysics Data System (ADS)

Sugiyama, Shigeki

2007-04-01

There are some computer vision systems that are available on a market but those are quite far from a real usage of our daily life in a sense of security guard or in a sense of a usage of recognition of a target object behaviour. Because those surroundings' sensing might need to recognize a detail description of an object, like "the distance to an object" and "an object detail figure" and "its figure of edging", which are not possible to have a clear picture of the mechanisms of them with the present recognition system. So for doing this, here studies on mechanisms of how a pair of human eyes can recognize a distance apart, an object edging, and an object in order to get basic essences of vision mechanisms. And those basic mechanisms of object recognition are simplified and are extended logically for applying to a computer vision system. Some of the results of these studies are introduced on this paper.

Development of a Small Thermoelectric Generators Prototype for Energy Harvesting from Low Temperature Waste Heat at Industrial Plant.

PubMed

Chiarotti, Ugo; Moroli, Valerio; Menchetti, Fernando; Piancaldini, Roberto; Bianco, Loris; Viotto, Alberto; Baracchini, Giulia; Gaspardo, Daniele; Nazzi, Fabio; Curti, Maurizio; Gabriele, Massimiliano

2017-03-01

A 39-W thermoelectric generator prototype has been realized and then installed in industrial plant for on-line trials. The prototype was developed as an energy harvesting demonstrator using low temperature cooling water waste heat as energy source. The objective of the research program is to measure the actual performances of this kind of device working with industrial water below 90 °C, as hot source, and fresh water at a temperature of about 15 °C, as cold sink. The article shows the first results of the research program. It was verified, under the tested operative conditions, that the produced electric power exceeds the energy required to pump the water from the hot source and cold sink to the thermoelectric generator unit if they are located at a distance not exceeding 50 m and the electric energy conversion efficiency is 0.33%. It was calculated that increasing the distance of the hot source and cold sink to the thermoelectric generator unit to 100 m the produced electric energy equals the energy required for water pumping, while reducing the distance of the hot source and cold sink to zero meters the developed unit produces an electric energy conversion efficiency of 0.61%.

Influence of laser power on the penetration depth and geometry of scanning tracks in selective laser melting

NASA Astrophysics Data System (ADS)

Stopyra, Wojciech; Kurzac, Jarosław; Gruber, Konrad; Kurzynowski, Tomasz; Chlebus, Edward

2016-12-01

SLM technology allows production of a fully functional objects from metal and ceramic powders, with true density of more than 99,9%. The quality of manufactured items in SLM method affects more than 100 parameters, which can be divided into fixed and variable. Fixed parameters are those whose value before the process should be defined and maintained in an appropriate range during the process, e.g. chemical composition and morphology of the powder, oxygen level in working chamber, heating temperature of the substrate plate. In SLM technology, five parameters are variables that optimal set allows to produce parts without defects (pores, cracks) and with an acceptable speed. These parameters are: laser power, distance between points, time of exposure, distance between lines and layer thickness. To develop optimal parameters thin walls or single track experiments are performed, to select the best sets narrowed to three parameters: laser power, exposure time and distance between points. In this paper, the effect of laser power on the penetration depth and geometry of scanned single track was shown. In this experiment, titanium (grade 2) substrate plate was used and scanned by fibre laser of 1064 nm wavelength. For each track width, height and penetration depth of laser beam was measured.

[The relationship between accommodative accuracy at different near-work distances and early-onset myopia].

PubMed

Yu, Q W; Zhang, P; Zhou, S B; Hu, Y; Ji, M X; Luo, Y C; You, H L; Yao, Z X

2016-07-01

To observe the accommodative accuracy of children with early-onset myopia at different near-work distances, and discuss the relationship between accommodative accuracy and early-onset myopia. This was a case-control study. Thirty-seven emmetropic children, 41 early-onset myopic children without correction, and 39 early-onset myopic children with spectacles, aged 7 to 13 years, were included. Measures of refractive errors and accommodative accuracy at four near-work distances, including 50 cm, 40 cm, 30 cm, and 20 cm, were made using the binocular fusion cross cylinder (FCC) of an automatic phoropter. Most candidates showed accommodative lags, including the children with emmetropia. The ratio of lags in all candidates at different near-work distances was 75.21% (50 cm), 87.18% (40 cm), 92.31% (30 cm), and 98.29% (20 cm), respectively. All accommodative accuracies became worse, and the accommodative lag ratio and values of FCC increased, along with the shortening of the distance. The difference in accommodative accuracy among groups was statistically significant at 30 cm (χ(2)=7.852, P= 0.020) and 20 cm (χ(2)=6.480, P=0.039). The values of FCC among groups were significantly different at 30 cm (F=3.626, P=0.030) and 20 cm (F=3.703, P=0.028), but not at 50 cm and 40 cm (P>0.05). In addition, the FCC values of 30 cm and 20 cm had a statistically significant difference between myopic children without correction [(1.25±0.44) D and (1.76±0.43) D] and emmetropic children [(0.95±0.52) D and (1.41±0.58) D] (P=0.012, 0.008). The correlation between diopters of myopia and accommodative accuracy at different nearwork distances was not statistically significant (P>0.05). However, the correlation between diopters of myopia and the accommodative lag value (FCC) at 20 cm was statistically significant (r=0.246, P=0.028). The closer the near-work distance is, the worse the accommodative accuracy is. This is more significant in early-onset myopia, especially myopia without correction, than emmetropia. Wearing spectacles may improve the threshold and sensitivity of accommodations, and the accommodative accuracy at near-work distances (<30 cm) to some extent. The poor accommodative accuracy at near-work distances may be not related to early-onset myopia, but the value of FCC (20 cm) is related to early-onset myopia. The higher the FCC value is, the higher the diopter is. (Chin J Ophthalmol, 2016, 52: 520-524).

Radio Telescopes' Precise Measurements Yield Rich Scientific Payoffs

NASA Astrophysics Data System (ADS)

2008-01-01

Having the sharpest pictures always is a big advantage, and a sophisticated radio-astronomy technique using continent-wide and even intercontinental arrays of telescopes is yielding extremely valuable scientific results in a wide range of specialties. That's the message delivered to the American Astronomical Society's meeting in Austin, Texas, by Mark Reid of the Harvard-Smithsonian Center for Astrophysics, a leading researcher in the field of ultra-precise astronomical position measurements. Very Long Baseline Interferometry provides extremely high precision that can extend use of the parallax technique to many more celestial objects. Parallax is a direct means of measuring cosmic distances by detecting the slight shift in an object’s apparent position in the sky caused by Earth’s orbital motion. Credit: Bill Saxton, NRAO/AUI/NSF "Using radio telescopes, we are measuring distances and motions of celestial bodies with unprecedented accuracy. That's helping us better understand many processes ranging from star formation to the scale of the entire Universe," Reid said. The observing technique, called Very Long Baseline Interferometry (VLBI), was pioneered in 1967, but has come into continuous use only in the past 10-15 years. The National Science Foundation's Very Long Baseline Array (VLBA), a system of 10 radio-telescope antennas ranging from Hawaii to the Caribbean, was dedicated in 1993. There are other VLBI systems in Europe and Asia, and large radio telescopes around the world cooperate regularly to increase sensitivity. VLBI observations routinely produce images hundreds of times more detailed than those made at visible-light wavelengths by the Hubble Space Telescope. Several groups of researchers from across the globe use the VLBA to study stellar nurseries in our own Milky Way Galaxy and measure distances to regions where new stars are forming. The key has been to improve measurement accuracy to a factor of a hundred times better than that produced by the highly successful Hipparcos satellite. Using small clouds of gas in star-forming regions that strongly amplify radio waves, called cosmic masers, the astronomers measured the tiny shift in the object's position in the sky caused by the Earth's orbit around the sun. This, in turn, yielded highly-accurate distances by the simple surveying technique of triangulation, the "gold standard" of distance measuring techniques available to astronomers. Dr. Mark Reid Dr. Mark Reid Credit: CfA Click image for high-resolution file (1.02 MB) "Knowing the distance accurately means we also know the luminosities, masses and ages of the young stars much more accurately, and that is vital to understanding how star formation works," Reid said. In addition, he pointed out, the VLBA observations have shown the motions of the young stars in the Milky Way are much more complicated than simple circular motion. Massive young stars appear to be born orbiting the Milky Way considerably slower than older stars. "This might be explained by the interaction of giant molecular clouds, the ultimate sites of massive star formation, as they "surf" spiral density waves in the Milky Way." An international team of scientists led by Reid has used VLBI to detect the slight change in apparent position of the object at the Milky Way's center caused by our Solar System's orbit around that center. "It takes our Solar System more than 200 million years to circle the center of our Galaxy, and yet we can detect that motion in only a couple weeks with the VLBA -- truly astounding!" Reid said. The VLBA studies of the Galactic Center have shown that an object called Sagittarius A* is at the exact gravitational center of our Galaxy. That means, the scientists say, that the object must be incredibly massive. "The VLBA measurements, combined with infrared observations of stellar orbits around this object, provide overwhelming evidence that it's a supermassive black hole," Reid explained. "These observations are also going to make it possible to re-define the coordinate system used to map the entire Galaxy," Reid added. Looking farther outward, astronomers achieved a longstanding goal of measuring the spin of another galaxy. In 2005, Reid and his colleagues measured both the rotational spin and the motion in space of the galaxy M33, nearly 2.4 million light-years from Earth. Astronomers in the 1920s had attempted such a feat, but their results were not accurate enough. "This achievement had to wait for the VLBA," Reid said. This and subsequent work has put strong limits on the amount of unseen "dark matter" around the giant Andromeda galaxy, which M33 orbits. A continuing goal is to use VLBI observations to measure the orbits of these and other galaxies within the Local Group of galaxies to which our own Milky Way belongs. VLBA The Very Long Baseline Array (VLBA), the National Radio Astronomy Observatory’s continent-wide radio-telescope system. The VLBA provides the greatest resolving power, or ability to see detail, of any instrument in astronomy. Credit: NRAO/AUI/NSF In 1999, astronomers set a new standard for a distance measurement outside the Local Group of galaxies when they used the VLBA to make a direct geometric distance measurement to a galaxy called NGC 4258, 23.5 million light-years from Earth. That measurement, accurate to within 7 percent, caused other scientists to revise their indirect-measurement techniques for the rest of the Universe. The NGC 4258 distance was calculated by measuring the motion of masers in a disk of gas containing water molecules and orbiting a supermassive black hole at the galaxy's center. "Now, other galaxies are being observed in hopes of extending direct distance measurement even farther out in the Universe," Reid said. "One candidate, called UGC 3789, at a distance of about 160 million light-years, will be measured with about 10 percent accuracy. Our goal is to further improve these measurements and to measure 5 to 10 other galaxies in order to determine the Hubble constant (the expansion rate of the Universe) to 3 percent accuracy. This would put limits on key parameters of the dark energy that apparently is accelerating the expansion of the Universe," Reid added. The kind of accurate measurement of distances and motions that VLBI observations provide can benefit numerous other areas of astronomy, Reid pointed out. For example, the distances to pulsars have been measured directly with the VLBA, yielding better understanding of their characteristics. The technique also could reveal planets circling some nearby stars. "Anytime you can do something as dramatic as improving measurement accuracy by a hundredfold, you're bound to get a great scientific payoff," Reid said. "We're looking forward to exciting new results in the coming years," he added. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

DDM at Work: Reply to comments on "Dependency distance: A new perspective on syntactic patterns in natural languages".

PubMed

Xu, Chunshan; Liang, Junying; Liu, Haitao

2017-07-01

We provide responses to the commentaries in this volume to evaluate, clarify and extend some of the arguments in Dependency distance: A new perspective on syntactic patterns in natural languages. Evidences show that DDM (dependency distance minimization) is an important linguistic universal, biologically or cognitively motivated, in shaping the language system. As a general tendency, DDM works quite well in theoretical argumentations as well as practical applications. However, this does not mean that DDM is the only linguistic universal that works: it is highly possible that other factors, which might be biologically, physically, socially or culturally motivated, work as well to jointly mold languages. Copyright © 2017 Elsevier B.V. All rights reserved.

Workplace health and safety issues among community nurses: a study regarding the impact on providing care to rural consumers

PubMed Central

Terry, Daniel; Lê, Quynh; Nguyen, Uyen; Hoang, Ha

2015-01-01

Objectives The objective of the study was to investigate the types of workplace health and safety issues rural community nurses encounter and the impact these issues have on providing care to rural consumers. Methods The study undertook a narrative inquiry underpinned by a phenomenological approach. Community nursing staff who worked exclusively in rural areas and employed in a permanent capacity were contacted among 13 of the 16 consenting healthcare services. All community nurses who expressed a desire to participate were interviewed. Data were collected using semistructured interviews with 15 community nurses in rural and remote communities. Thematic analysis was used to analyse interview data. Results The role, function and structures of community nursing services varied greatly from site to site and were developed and centred on meeting the needs of individual communities. In addition, a number of workplace health and safety challenges were identified and were centred on the geographical, physical and organisational environment that community nurses work across. The workplace health and safety challenges within these environments included driving large distances between client’s homes and their office which lead to working in isolation for long periods and without adequate communication. In addition, other issues included encountering, managing and developing strategies to deal with poor client and carer behaviour; working within and negotiating working environments such as the poor condition of patient homes and clients smoking; navigating animals in the workplace; vertical and horizontal violence; and issues around workload, burnout and work-related stress. Conclusions Many nurses achieved good outcomes to meet the needs of rural community health consumers. Managers were vital to ensure that service objectives were met. Despite the positive outcomes, many processes were considered unsafe by community nurses. It was identified that greater training and capacity building are required to meet the needs among all staff. PMID:26270947

Improving CNN Performance Accuracies With Min-Max Objective.

PubMed

Shi, Weiwei; Gong, Yihong; Tao, Xiaoyu; Wang, Jinjun; Zheng, Nanning

2017-06-09

We propose a novel method for improving performance accuracies of convolutional neural network (CNN) without the need to increase the network complexity. We accomplish the goal by applying the proposed Min-Max objective to a layer below the output layer of a CNN model in the course of training. The Min-Max objective explicitly ensures that the feature maps learned by a CNN model have the minimum within-manifold distance for each object manifold and the maximum between-manifold distances among different object manifolds. The Min-Max objective is general and able to be applied to different CNNs with insignificant increases in computation cost. Moreover, an incremental minibatch training procedure is also proposed in conjunction with the Min-Max objective to enable the handling of large-scale training data. Comprehensive experimental evaluations on several benchmark data sets with both the image classification and face verification tasks reveal that employing the proposed Min-Max objective in the training process can remarkably improve performance accuracies of a CNN model in comparison with the same model trained without using this objective.

Non-interferometric deep optical resolution photoacoustic remote sensing microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

HajiReza, Parsin H.; Bell, Kevan L.; Shi, Wei; Zemp, Roger J.

2017-03-01

A novel all-optical non-contact photoacoustic microscopy system is introduced. The confocal configuration is used to ensure detection of initial pressure shock wave-induced intensity reflections at the subsurface origin where pressures are largest. Phantom studies confirm signal dependence on optical absorption, index-contrast, and excitation fluence. Taking advantage of a focused1310 nm interrogation beam, the penetration depth of the system is improved to 2mm for an optical resolution system. High signal-to-noise ratios (>60dB) with 2.5 cm working distance from the objective lens to the sample is achieved. Real-time in-vivo imaging of microvasculature and melanoma tumors are demonstrated.

Understanding the Financial Knowledge Gap: A New Dimension of Inequality in Later Life.

PubMed

Khan, Mohammad Nuruzzaman; Rothwell, David W; Cherney, Katrina; Sussman, Tamara

2017-01-01

To understand individuals' financial behaviors, it is important to understand the financial knowledge gap - the distance between one's objective and subjective financial knowledge. Overestimating one's financial knowledge can lead to risky financial behaviors. To date, limited empirical work has examined how financial knowledge gap varies across age groups. We analyze the size and nature of the financial knowledge gap and its variation across age groups. Using nationally representative data, we find robust evidence that older adults overestimate their financial knowledge. Social workers can assess the financial knowledge gap and educate their clients to protect from financial fraud, exploitation, and abuse.

Low-metallicity (sub-SMC) massive stars

NASA Astrophysics Data System (ADS)

Garcia, Miriam; Herrero, Artemio; Najarro, Francisco; Camacho, Inés; Lennon, Daniel J.; Urbaneja, Miguel A.; Castro, Norberto

2017-11-01

The double distance and metallicity frontier marked by the SMC has been finally broken with the aid of powerful multi-object spectrographs installed at 8-10m class telescopes. VLT, GTC and Keck have enabled studies of massive stars in dwarf irregular galaxies of the Local Group with poorer metal-content than the SMC. The community is working to test the predictions of evolutionary models in the low-metallicity regime, set the new standard for the metal-poor high-redshift Universe, and test the extrapolation of the physics of massive stars to environments of decreasing metallicity. In this paper, we review current knowledge on this topic.

Practical algorithms for simulation and reconstruction of digital in-line holograms.

PubMed

Latychevskaia, Tatiana; Fink, Hans-Werner

2015-03-20

Here we present practical methods for simulation and reconstruction of in-line digital holograms recorded with plane and spherical waves. The algorithms described here are applicable to holographic imaging of an object exhibiting absorption as well as phase-shifting properties. Optimal parameters, related to distances, sampling rate, and other factors for successful simulation and reconstruction of holograms are evaluated and criteria for the achievable resolution are worked out. Moreover, we show that the numerical procedures for the reconstruction of holograms recorded with plane and spherical waves are identical under certain conditions. Experimental examples of holograms and their reconstructions are also discussed.

Logo recognition in video by line profile classification

NASA Astrophysics Data System (ADS)

den Hollander, Richard J. M.; Hanjalic, Alan

2003-12-01

We present an extension to earlier work on recognizing logos in video stills. The logo instances considered here are rigid planar objects observed at a distance in the scene, so the possible perspective transformation can be approximated by an affine transformation. For this reason we can classify the logos by matching (invariant) line profiles. We enhance our previous method by considering multiple line profiles instead of a single profile of the logo. The positions of the lines are based on maxima in the Hough transform space of the segmented logo foreground image. Experiments are performed on MPEG1 sport video sequences to show the performance of the proposed method.

Laboratory simulations of astrophysical jets: results from experiments at the PF-3, PF-1000U, and KPF-4 facilities

NASA Astrophysics Data System (ADS)

Krauz, V. I.; Myalton, V. V.; Vinogradov, V. P.; Velikhov, E. P.; Ananyev, S. S.; Dan'ko, S. A.; Kalinin, Yu G.; Kharrasov, A. M.; Vinogradova, Yu V.; Mitrofanov, K. N.; Paduch, M.; Miklaszewski, R.; Zielinska, E.; Skladnik-Sadowska, E.; Sadowski, M. J.; Kwiatkowski, R.; Tomaszewski, K.; Vojtenko, D. A.

2017-10-01

Results are presented from laboratory simulations of plasma jets emitted by young stellar objects carried out at the plasma focus facilities. The experiments were performed at three facilities: the PF-3, PF-1000U and KPF-4. The operation modes were realized enabling the formation of narrow plasma jets which can propagate over long distances. The main parameters of plasma jets and background plasma were determined. In order to control the ratio of a jet density to that of background plasma, some special operation modes with pulsed injection of the working gas were used.

Autofocusing in digital holography using deep learning

NASA Astrophysics Data System (ADS)

Ren, Zhenbo; Xu, Zhimin; Lam, Edmund Y.

2018-02-01

In digital holography, it is critical to know the distance in order to reconstruct the multi-sectional object. This autofocusing is traditionally solved by reconstructing a stack of in-focus and out-of-focus images and using some focus metric, such as entropy or variance, to calculate the sharpness of each reconstructed image. Then the distance corresponding to the sharpest image is determined as the focal position. This method is effective but computationally demanding and time-consuming. To get an accurate estimation, one has to reconstruct many images. Sometimes after a coarse search, a refinement is needed. To overcome this problem in autofocusing, we propose to use deep learning, i.e., a convolutional neural network (CNN), to solve this problem. Autofocusing is viewed as a classification problem, in which the true distance is transferred as a label. To estimate the distance is equated to labeling a hologram correctly. To train such an algorithm, totally 1000 holograms are captured under the same environment, i.e., exposure time, incident angle, object, except the distance. There are 5 labels corresponding to 5 distances. These data are randomly split into three datasets to train, validate and test a CNN network. Experimental results show that the trained network is capable of predicting the distance without reconstructing or knowing any physical parameters about the setup. The prediction time using this method is far less than traditional autofocusing methods.

Single-beam Denisyuk holograms recording with pulsed 30Hz RGB laser

NASA Astrophysics Data System (ADS)

Zacharovas, Stanislovas; Bakanas, Ramūnas; Stankauskas, Algimantas

2016-03-01

It is well known fact that holograms can be recorded either by continuous wave (CW) laser, or by single pulse coming from pulsed laser. However, multi-pulse or multiple-exposure holograms were used only in interferometry as well as for information storage. We have used Geola's single longitudinal mode pulsed RGB laser to record Denisyuk type holograms. We successfully recorded objects situated at the distance of more than 30cm, employing the multi-pulse working regime of the laser. To record Denisyuk hologram we have used 50 ns duration 440, 660nm wavelength and 35ns duration 532nm wavelength laser pulses at the repetition rate of 30Hz. As photosensitive medium we have used Slavich-Geola PFG-03C glass photoplate. Radiations with different wavelengths were mixed into "white" beam, collimated and directed onto the photoplate. For further objects illumination an additional flat silver coated mirror was used.

Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling.

PubMed

Kehr, S C; Liu, Y M; Martin, L W; Yu, P; Gajek, M; Yang, S-Y; Yang, C-H; Wenzel, M T; Jacob, R; von Ribbeck, H-G; Helm, M; Zhang, X; Eng, L M; Ramesh, R

2011-01-01

A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, as propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of λ/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy and thermal sensors.

A New Distance Metric for Unsupervised Learning of Categorical Data.

PubMed

Jia, Hong; Cheung, Yiu-Ming; Liu, Jiming

2016-05-01

Distance metric is the basis of many learning algorithms, and its effectiveness usually has a significant influence on the learning results. In general, measuring distance for numerical data is a tractable task, but it could be a nontrivial problem for categorical data sets. This paper, therefore, presents a new distance metric for categorical data based on the characteristics of categorical values. In particular, the distance between two values from one attribute measured by this metric is determined by both the frequency probabilities of these two values and the values of other attributes that have high interdependence with the calculated one. Dynamic attribute weight is further designed to adjust the contribution of each attribute-distance to the distance between the whole data objects. Promising experimental results on different real data sets have shown the effectiveness of the proposed distance metric.

Making Distance Visible: Assembling Nearness in an Online Distance Learning Programme

ERIC Educational Resources Information Center

Ross, Jen; Gallagher, Michael Sean; Macleod, Hamish

2013-01-01

Online distance learners are in a particularly complex relationship with the educational institutions they belong to (Bayne, Gallagher, & Lamb, 2012). For part-time distance students, arrivals and departures can be multiple and invisible as students take courses, take breaks, move into independent study phases of a programme, find work or…

How far is it? Distance measurements and their consequences

NASA Astrophysics Data System (ADS)

Krełowski, Jacek

2017-08-01

Methods of measuring distances to objects in our Milky Way are briefly discussed. They generally base on three principles: of using a standard rod, of standard candle and of column density of interstellar matter. Weak and strong points of these methods are presented. The presence of gray extinction towards some objects is suggested which makes the most universal method of standard candle (spectroscopic parallax) very uncertain. Hard to say whether gray extinc-tion appears only in the form of circumstellar debris discs or is present also in the general interstellar medium. The application of the method of measuring column densities of interstellar gases suggests that the rotation curve of our Milky Way system is rather Keplerian than flat which creates doubts as to whether any Dark Matter halo is present around our Galaxy. It is emphasized that the most universal method, i.e. that of standard candle, used to estimate distances to cosmological objects, may suffer serious errors because of improper subtraction of extinction effects.

[Binocular fusion method for prevention of myopia].

PubMed

Xu, G D

1989-03-01

When looking at a far object with two eyes, relaxation of convergence and accommodation occurred and accompanied by binocular fusion. Using this phenomenon a method of binocular fusion of targets was designed, that is the distance between two targets are just the same as the distance between two visual lines, while looking at a far object. During the images of the targets are fused, the accommodation and convergence are relaxed concomitantly; thus a result of correction of pseudomyopia and prevention of myopia is achieved. By means of binocular fusion, the eye muscle exercises were conducted and resulted in not only the far point further but also the near point closer. The skiascopic examination carried out at the same time of binocular fusion showed that the degrees of relaxed accommodation was 97.9% that of looking at an object in far distance. The above results indicated that the binocular fusion method had excellent effect on the prevention of myopia. This method is simple and feasible, conforms to the visual physiology, and thus can be widely adopted.

Mental Representation of Spatial Cues During Spaceflight (3D-SPACE)

NASA Astrophysics Data System (ADS)

Clement, Gilles; Lathan, Corinna; Skinner, Anna; Lorigny, Eric

2008-06-01

The 3D-SPACE experiment is a joint effort between ESA and NASA to develop a simple virtual reality platform to enable astronauts to complete a series of tests while aboard the International Space Station (ISS). These tests will provide insights into the effects of the space environment on: (a) depth perception, by presenting 2D geometric illusions and 3D objects that subjects adjust with a finger trackball; (b) distance perception, by presenting natural or computer-generated 3D scenes where subjects estimate and report absolute distances or adjust distances; and (c) handwriting/drawing, by analyzing trajectories and velocities when subjects write or draw memorized objects with an electronic pen on a digitizing tablet. The objective of these tasks is to identify problems associated with 3D perception in astronauts with the goal of developing countermeasures to alleviate any associated performance risks. The equipment has been uploaded to the ISS in April 2008, and the first measurements should take place during Increment 17.

Developing the Fundamental Theorem of Calculus. Applications of Calculus to Work, Area, and Distance Problems. [and] Atmospheric Pressure in Relation to Height and Temperature. Applications of Calculus to Atmospheric Pressure. [and] The Gradient and Some of Its Applications. Applications of Multivariate Calculus to Physics. [and] Kepler's Laws and the Inverse Square Law. Applications of Calculus to Physics. UMAP Units 323, 426, 431, 473.

ERIC Educational Resources Information Center

Lindstrom, Peter A.; And Others

This document consists of four units. The first of these views calculus applications to work, area, and distance problems. It is designed to help students gain experience in: 1) computing limits of Riemann sums; 2) computing definite integrals; and 3) solving elementary area, distance, and work problems by integration. The second module views…

Automated Inspection of Power Line Corridors to Measure Vegetation Undercut Using Uav-Based Images

NASA Astrophysics Data System (ADS)

Maurer, M.; Hofer, M.; Fraundorfer, F.; Bischof, H.

2017-08-01

Power line corridor inspection is a time consuming task that is performed mostly manually. As the development of UAVs made huge progress in recent years, and photogrammetric computer vision systems became well established, it is time to further automate inspection tasks. In this paper we present an automated processing pipeline to inspect vegetation undercuts of power line corridors. For this, the area of inspection is reconstructed, geo-referenced, semantically segmented and inter class distance measurements are calculated. The presented pipeline performs an automated selection of the proper 3D reconstruction method for on the one hand wiry (power line), and on the other hand solid objects (surrounding). The automated selection is realized by performing pixel-wise semantic segmentation of the input images using a Fully Convolutional Neural Network. Due to the geo-referenced semantic 3D reconstructions a documentation of areas where maintenance work has to be performed is inherently included in the distance measurements and can be extracted easily. We evaluate the influence of the semantic segmentation according to the 3D reconstruction and show that the automated semantic separation in wiry and dense objects of the 3D reconstruction routine improves the quality of the vegetation undercut inspection. We show the generalization of the semantic segmentation to datasets acquired using different acquisition routines and to varied seasons in time.

Duration, distance, and speed judgments of two moving objects by 4- to 11-year olds.

PubMed

Matsuda, F

1996-11-01

Four- to 11-year-old children (N = 133) made duration, distance, and speed judgments on a Piagetian task where two cars ran on two parallel tracks. Special effort was made to make duration judgment tasks and distance judgment tasks comparable. Among younger children, difficulties of duration judgments and distance judgments were approximately the same. Additionally, temporal attributes had nearly the same effects on duration judgments as spatial attributes had on distance judgments, and spatial attributes had nearly the same effects on duration judgments as temporal attributes had on distance judgments. Among older children, distance judgments were easier than duration judgments, and the above-mentioned symmetry in effects of temporal and spatial attributes decreased somewhat. Temporal and spatial attributes affected speed judgments equally, across age groups.

Why Wheels Work.

ERIC Educational Resources Information Center

Stepp, Richard D.

1982-01-01

Discusses how the wheel works. The inherent mechanical advantage of wheel-and-axle system is that it reduced the distance the load-bearing surfaces have to slip relative to one another when the whole apparatus advances some given distance reducing (with leverage) the force needed to propel the system. (Author/JN)

Distance Education: More Work, Same Pay for Faculty!

ERIC Educational Resources Information Center

Saba Farhad, Ed.

2000-01-01

Considers workload and pay issues for faculty in distance education courses, and maintains that faculty are doing more work for the same pay. Discusses costs of technology-based instruction; the emerging trend of partnerships in education; venture capital; and the role of the Department of Defense. (LRW)

Learning object correspondences with the observed transport shape measure.

PubMed

Pitiot, Alain; Delingette, Hervé; Toga, Arthur W; Thompson, Paul M

2003-07-01

We propose a learning method which introduces explicit knowledge to the object correspondence problem. Our approach uses an a priori learning set to compute a dense correspondence field between two objects, where the characteristics of the field bear close resemblance to those in the learning set. We introduce a new local shape measure we call the "observed transport measure", whose properties make it particularly amenable to the matching problem. From the values of our measure obtained at every point of the objects to be matched, we compute a distance matrix which embeds the correspondence problem in a highly expressive and redundant construct and facilitates its manipulation. We present two learning strategies that rely on the distance matrix and discuss their applications to the matching of a variety of 1-D, 2-D and 3-D objects, including the corpus callosum and ventricular surfaces.

Force That Increases at Larger Distance Has Some Psychological and Astronomical Evidence Supporting its Existence

NASA Astrophysics Data System (ADS)

Struck, James

2011-09-01

Force that Increases with distance is different than dark energy as I am arguing for existence of force based on psychological and astronomical bases. Hubble shift, doppler shift, comet return, quasar zoo and quasars and psychological evidence of interest in distant objects lends support to a force like gravity, nuclear, weak, strong, virtual, decay, biological, growth forces which increases its intensity with distance unlike gravity which decreases in intensity with distance. Jane Frances Back Struck contributed to this finding with her request that her grandparents have "perfect justice" even though her grandparents had died before she was born; interest increasing with distance from grandparents.

The deep fovea, sideways vision and spiral flight paths in raptors.

PubMed

Tucker, V A

2000-12-01

Raptors - falcons, hawks and eagles in this study - have two regions of the retina in each eye that are specialized for acute vision: the deep fovea and the shallow fovea. The line of sight of the deep fovea points forwards and approximately 45 degrees to the right or left of the head axis, while that of the shallow fovea also points forwards but approximately 15 degrees to the right or left of the head axis. The anatomy of the foveae suggests that the deep fovea has the higher acuity. Several species of raptors in this study repeatedly moved their heads among three positions while looking at an object: straight, with the head axis pointing towards the object; or sideways to the right or left, with the head axis pointing approximately 40 degrees to the side of the object. Since raptors do not rotate their eyes noticeably in the sockets, these movements presumably cause the image of the object to fall on the shallow and deep foveae. The movements occurred approximately every 2 s on average in hawks and falcons, and approximately every 5 s in bald eagles. The proportion of time that the raptors spent looking straight or sideways at an object depended on how far away the object was. At a distances closer than 8 m, they spent more time looking at the object straight, but as the distance increased to 21 m, they spent more time looking at it sideways. At distances of 40 m or more, raptors looked sideways at the object 80 % or more of the time. This dependence of head position on distance suggests that raptors use their more acute sideways vision to look at distant objects and sacrifice acuity for stereoscopic binocular vision to look at close objects. Having their most acute vision towards the side causes a conflict in raptors such as falcons, which dive at prey from great distances at high speeds: at a speed of 70 m s(-)(1), turning their head sideways to view the prey straight ahead with high visual acuity may increase aerodynamic drag by a factor of 2 or more and slow the raptor down. Raptors could resolve this conflict by diving along a logarithmic spiral path with their head straight and one eye looking sideways at the prey, rather than following the straight path to the prey with their head turned sideways. Although the spiral path is longer than the straight path, a mathematical model for an 'ideal falcon' shows that the falcon could reach the prey more quickly along the spiral path because the speed advantage of a straight head more than compensates for the longer path.

Radio Astronomers Set New Standard for Accurate Cosmic Distance Measurement

NASA Astrophysics Data System (ADS)

1999-06-01

A team of radio astronomers has used the National Science Foundation's Very Long Baseline Array (VLBA) to make the most accurate measurement ever made of the distance to a faraway galaxy. Their direct measurement calls into question the precision of distance determinations made by other techniques, including those announced last week by a team using the Hubble Space Telescope. The radio astronomers measured a distance of 23.5 million light-years to a galaxy called NGC 4258 in Ursa Major. "Ours is a direct measurement, using geometry, and is independent of all other methods of determining cosmic distances," said Jim Herrnstein, of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. The team says their measurement is accurate to within less than a million light-years, or four percent. The galaxy is also known as Messier 106 and is visible with amateur telescopes. Herrnstein, along with James Moran and Lincoln Greenhill of the Harvard- Smithsonian Center for Astrophysics; Phillip Diamond, of the Merlin radio telescope facility at Jodrell Bank and the University of Manchester in England; Makato Inoue and Naomasa Nakai of Japan's Nobeyama Radio Observatory; Mikato Miyoshi of Japan's National Astronomical Observatory; Christian Henkel of Germany's Max Planck Institute for Radio Astronomy; and Adam Riess of the University of California at Berkeley, announced their findings at the American Astronomical Society's meeting in Chicago. "This is an incredible achievement to measure the distance to another galaxy with this precision," said Miller Goss, NRAO's Director of VLA/VLBA Operations. "This is the first time such a great distance has been measured this accurately. It took painstaking work on the part of the observing team, and it took a radio telescope the size of the Earth -- the VLBA -- to make it possible," Goss said. "Astronomers have sought to determine the Hubble Constant, the rate of expansion of the universe, for decades. This will in turn lead to an estimate of the age of the universe. In order to do this, you need an unambiguous, absolute distance to another galaxy. We are pleased that the NSF's VLBA has for the first time determined such a distance, and thus provided the calibration standard astronomers have always sought in their quest for accurate distances beyond the Milky Way," said Morris Aizenman, Executive Officer of the National Science Foundation's (NSF) Division of Astronomical Sciences. "For astronomers, this measurement is the golden meter stick in the glass case," Aizenman added. The international team of astronomers used the VLBA to measure directly the motion of gas orbiting what is generally agreed to be a supermassive black hole at the heart of NGC 4258. The orbiting gas forms a warped disk, nearly two light-years in diameter, surrounding the black hole. The gas in the disk includes water vapor, which, in parts of the disk, acts as a natural amplifier of microwave radio emission. The regions that amplify radio emission are called masers, and work in a manner similar to the way a laser amplifies light emission. Determining the distance to NGC 4258 required measuring motions of extremely small shifts in position of these masers as they rotate around the black hole. This is equivalent to measuring an angle one ten-thousandth the width of a human hair held at arm's length. "The VLBA is the only instrument in the world that could do this," said Moran. "This work is the culmination of a 20-year effort at the Harvard Smithsonian Center for Astrophysics to measure distances to cosmic masers," said Irwin Shapiro, Director of that institution. Collection of the data for the NGC 4258 project was begun in 1994 and was part of Herrnstein's Ph.D dissertation at Harvard University. Previous observations with the VLBA allowed the scientists to measure the speed at which the gas is orbiting the black hole, some 39 million times more massive than the Sun. They did this by observing the amount of change in the wavelength of the radio waves caused by the Doppler effect. The gas is orbiting at a speed of more than two million miles per hour. The orbiting disk of gas is almost edge-on as viewed from Earth. The astronomers obtained the orbital speeds and the positions of the masers in the disk by measuring the Doppler Shift of the masers at the disk's sides, where the gas is moving almost directly away from the Earth on one side and toward the Earth on the other. Measurements of the different orbital speeds at different distances from the black hole, made in 1994, allowed them to determine the mass of the black hole. These measurements required the great resolving power, or ability to see fine detail, of the VLBA. This picture of an orbiting disk was confirmed by measurement of centrifugal acceleration, according to the scientists. The newest observations were focused on maser "spots" on the near edge of the disk, where orbital motion shifts their position in the sky, though by an extremely small amount. The VLBA, however, was able to detect this extremely small movement, called "proper motion" by astronomers. This motion was detected by observing the galaxy at 4- to 8-month intervals over more than three years. "By knowing the speed at which the gas is orbiting and then measuring its motion across the sky, we can use plain old trigonometry to calculate the distance," Greenhill said. He added, however, that "you need a bit of luck to be able to do this. So far, we know of only 22 galaxies with water masers in their nuclear regions that also are relatively nearby. Then, the geometry of the disk, relative to Earth, has to be right to allow us to make such a measurement" The VLBA measurement of NGC 4258's distance differs significantly from the distance to that galaxy determined through HST observations of Cepheid variable stars. Using such stars, a team of astronomers led by University of California-Berkeley scientist Eyal Maoz has made preliminary and as-yet unpublished estimates of the distance to NGC 4258 as either 27 or 29 million light-years, depending on assumptions about the characteristics of this type of star in that galaxy. Other Cepheid-based galaxy distances were used to calculate the expansion rate of the universe, called the Hubble Constant, announced by a team of HST observers last week. "This difference could mean that there may be more uncertainty in Cepheid-determined distances than people have realized," said Moran. "Providing this directly-determined distance to one galaxy -- a distance that can serve as a milestone -- should be helpful in determining distances to other galaxies, and thus the Hubble Constant and the size and age of the universe" The VLBA is a system of ten radio-telescope antennas, each 25 meters (82 feet) in diameter, stretching some 5,000 miles from Mauna Kea in Hawaii to St. Croix in the U.S. Virgin Islands. Operated from NRAO's Array Operations Center in Socorro, NM, the VLBA offers astronomers the greatest resolving power of any telescope anywhere. The NRAO is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. Background information: Determining Cosmic Distances Determining cosmic distances obviously is vital to understanding the size of the universe. In turn, knowing the size of the universe is an important step in determining its age. "The size puts a limit on how much expansion could have occurred since the Big Bang, and thus tells us something about the age," said Moran. However, determining cosmic distances has proven to be a particularly thorny problem for astronomers. In the third century, B.C., the Greek astronomer Aristarchus devised a method of using trigonometry to determine the relative distances of the Moon and Sun, but in practice his method was difficult to use. Though a great first step, he missed the mark by a factor of 20. It wasn't until 1761 that trigonometric methods produced a relatively accurate distance to Venus, thus calibrating the size of the Solar System. The first accurate distance to another star was determined trigonometrically by Friedrich Wilhelm Bessel in 1838. Traditional trigonometric methods of measuring celestial distances require extremely accurate measurement of an object's position in the sky. By measuring the apparent shift in an object's position, called parallax, caused by the Earth's journey around the Sun, the distance to the object can be calculated. Until recent years, such measurements were limited by the atmosphere's degrading effect on optical observations. Recently, the Hipparcos satellite has measured stellar distances accurate to within 10 percent out to about 300 light-years. Beyond the range of parallax measurements, astronomers were forced to use indirect methods of estimating distances. Many of these methods make presumptions about the intrinsic brightness of objects, then estimate the distance by measuring how much fainter they appear on Earth. The faintness is presumed to be caused by the distance, according to the inverse-square law (doubling of the distance reduces brightness by a factor of four). Thus, stars of a particular spectral class are all presumed to be of the same intrinsic brightness. Such techniques have been used to estimate distances of stars out to about 25,000 light-years, still not far enough to estimate distance beyond our own Milky Way Galaxy. Early in the 20th Century, Henrietta Leavitt, of Harvard College Observatory, discovered that variable-brightness stars known as Cepheid variables showed a useful property -- the longer their pulsation periods, the brighter they are intrinsically. Once the absolute distance to a few Cepheids was determined, these stars were used to measure distances beyond the Milky Way. In the 1920s, Edwin Hubble used Cepheid-variable distance determinations to show that, contrary to then-prevalent opinion, many "nebulae" were, in fact, other galaxies far distant from our own. Distances determined using Cepheid variables, along with measurements of the Doppler shift of other galaxies' light, allowed Hubble to discover the expansion of the universe, the basis of the Big Bang theory. The Cepheid technique still is one of the building blocks of the extragalactic distance scale. However, because of absorption of light by interstellar dust and subtle differences among the stars themselves, this technique is subject to considerable uncertainty. Similarly, techniques that use a specific type of supernova (Type Ia) presumed to be of uniform intrinsic brightness, while able to make distance estimates farther than the Cepheid technique, still are subject to uncertainties. The NSF's VLBA, with resolving power hundreds of times better than even the Hubble Space Telescope, has allowed direct trigonometric techniques to be applied in measuring much greater distances than ever before. The VLBA measured the expansion of the shell of exploding debris from the supernova SN 1993J in the galaxy M81, 11 million light- years away. This information, combined with optical observations that measured the speed of the expanding debris by the Doppler shift of its emitted spectral lines, allowed a trigonometric calculation of the distance to M81. Now, with the VLBA's direct measurement of motions in the gas disk surrounding NGC 4258, trigonometric measurement, not subject to the vagaries of dust absorption and other uncertaintities in an object's brightness, has been extended to a distance of more than 23 million light-years.

Design Support System for Open Distance Learning Student Teamwork

NASA Astrophysics Data System (ADS)

Putranto, A.; Pradipto, Y. D.

2017-01-01

Open distance learning students in doing team assignment, they seldom face to some problems such as student fell unfair in numbers of workload contribution, instructors also do not know which students do more work than others. So there are some questions ie: how to connect between instructor, team members, and working documents. Methods will be used are first, analyzing current condition and last by designing systems to connect between instructor, team members, and document. The expected result is support systems for open distance learning student teamwork.

The new confocal heavy ion microprobe beamline at ANSTO: The first microprobe resolution tests and applications for elemental imaging and analysis

NASA Astrophysics Data System (ADS)

Pastuovic, Z.; Siegele, R.; Cohen, D. D.; Mann, M.; Ionescu, M.; Button, D.; Long, S.

2017-08-01

The Centre for Accelerator Science facility at ANSTO has been expanded with the new NEC 6 MV ;SIRIUS; accelerator system in 2015. In this paper we present a detailed description of the new nuclear microprobe-Confocal Heavy Ion Micro-Probe (CHIMP) together with results of the microprobe resolution testing and the elemental analysis performed on typical samples of mineral ore deposits and hyper-accumulating plants regularly measured at ANSTO. The CHIMP focusing and scanning systems are based on the OM-150 Oxford quadrupole triplet and the OM-26 separated scan-coil doublet configurations. A maximum ion rigidity of 38.9 amu-MeV was determined for the following nuclear microprobe configuration: the distance from object aperture to collimating slits of 5890 mm, the working distance of 165 mm and the lens bore diameter of 11 mm. The overall distance from the object to the image plane is 7138 mm. The CHIMP beamline has been tested with the 3 MeV H+ and 6 MeV He2+ ion beams. The settings of the object and collimating apertures have been optimized using the WinTRAX simulation code for calculation of the optimum acceptance settings in order to obtain the highest possible ion current for beam spot sizes of 1 μm and 5 μm. For optimized aperture settings of the CHIMP the beam brightness was measured to be ∼0.9 pA μm-2 mrad-2 for 3 MeV H+ ions, while the brightness of ∼0.4 pA μm-2 mrad-2 was measured for 6 MeV He2+ ions. The smallest beam sizes were achieved using a microbeam with reduced particle rate of 1000 Hz passing through the object slit apertures several micrometers wide. Under these conditions a spatial resolution of ∼0.6 μm × 1.5 μm for 3 MeV H+ and ∼1.8 μm × 1.8 μm for 6 MeV He2+ microbeams in horizontal (and vertical) dimension has been achieved. The beam sizes were verified using STIM imaging on 2000 and 1000 mesh Cu electron microscope grids.

Influence of semantic consistency and perceptual features on visual attention during scene viewing in toddlers.

PubMed

Helo, Andrea; van Ommen, Sandrien; Pannasch, Sebastian; Danteny-Dordoigne, Lucile; Rämä, Pia

2017-11-01

Conceptual representations of everyday scenes are built in interaction with visual environment and these representations guide our visual attention. Perceptual features and object-scene semantic consistency have been found to attract our attention during scene exploration. The present study examined how visual attention in 24-month-old toddlers is attracted by semantic violations and how perceptual features (i. e. saliency, centre distance, clutter and object size) and linguistic properties (i. e. object label frequency and label length) affect gaze distribution. We compared eye movements of 24-month-old toddlers and adults while exploring everyday scenes which either contained an inconsistent (e.g., soap on a breakfast table) or consistent (e.g., soap in a bathroom) object. Perceptual features such as saliency, centre distance and clutter of the scene affected looking times in the toddler group during the whole viewing time whereas looking times in adults were affected only by centre distance during the early viewing time. Adults looked longer to inconsistent than consistent objects either if the objects had a high or a low saliency. In contrast, toddlers presented semantic consistency effect only when objects were highly salient. Additionally, toddlers with lower vocabulary skills looked longer to inconsistent objects while toddlers with higher vocabulary skills look equally long to both consistent and inconsistent objects. Our results indicate that 24-month-old children use scene context to guide visual attention when exploring the visual environment. However, perceptual features have a stronger influence in eye movement guidance in toddlers than in adults. Our results also indicate that language skills influence cognitive but not perceptual guidance of eye movements during scene perception in toddlers. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of jamming efficiency for the protection of a single ground object

NASA Astrophysics Data System (ADS)

Matuszewski, Jan

2018-04-01

The electronic countermeasures (ECM) include methods to completely prevent or restrict the effective use of the electromagnetic spectrum by the opponent. The most widespread means of disorganizing the operation of electronic devices is to create active and passive radio-electronic jamming. The paper presents the way of jamming efficiency calculations for protecting ground objects against the radars mounted on the airborne platforms. The basic mathematical formulas for calculating the efficiency of active radar jamming are presented. The numerical calculations for ground object protection are made for two different electronic warfare scenarios: the jammer is placed very closely and in a determined distance from the protecting object. The results of these calculations are presented in the appropriate figures showing the minimal distance of effective jamming. The realization of effective radar jamming in electronic warfare systems depends mainly on the precise knowledge of radar and the jammer's technical parameters, the distance between them, the assumed value of the degradation coefficient, the conditions of electromagnetic energy propagation and the applied jamming method. The conclusions from these calculations facilitate making a decision regarding how jamming should be conducted to achieve high efficiency during the electronic warfare training.

A simple but powerful theory of the moon illusion.

PubMed

Baird, J C; Wagner, M; Fuld, K

1990-08-01

Modification of Restle's theory (1970) explains the moon illusion and related phenomena on the basis of three principles: (1) The apparent sizes of objects are their perceived visual angles. (2) The apparent size of the moon is determined by the ratio of the angular extent of the moon relative to the extents subtended by objects composing the surrounding context, such as the sky and things on the ground. (3) The visual extents subtended by common objects of a constant physical size decrease systematically with increasing distance from the observer. Further development of this theory requires specification of both the components of the surrounding context and their relative importance in determining the apparent size and distance of the moon.

Object Locating System

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)

2000-01-01

A portable system is provided that is operational for determining, with three dimensional resolution, the position of a buried object or approximately positioned object that may move in space or air or gas. The system has a plurality of receivers for detecting the signal front a target antenna and measuring the phase thereof with respect to a reference signal. The relative permittivity and conductivity of the medium in which the object is located is used along with the measured phase signal to determine a distance between the object and each of the plurality of receivers. Knowing these distances. an iteration technique is provided for solving equations simultaneously to provide position coordinates. The system may also be used for tracking movement of an object within close range of the system by sampling and recording subsequent position of the object. A dipole target antenna. when positioned adjacent to a buried object, may be energized using a separate transmitter which couples energy to the target antenna through the medium. The target antenna then preferably resonates at a different frequency, such as a second harmonic of the transmitter frequency.

Operating a Distance Learning Module within an Undergraduate Work Placement: Some Reflections.

ERIC Educational Resources Information Center

Gammie, Elizabeth; Gammie, Bob; Duncan, Fiona

2002-01-01

A distance learning module on auditing was implemented for accounting students on a 1-year full-time work placement. Review of stakeholder focus groups showed that they considered the module innovative; there were concerns about standards and equity. Initial groundwork with stakeholders, especially professional organizations and external…

Work and Learning: The Implications for Thai Transnational Distance Learners

ERIC Educational Resources Information Center

Crossman, Joanna

2005-01-01

The paper describes a qualitative study concerning the experiences of nine Thai transnational distance learners enrolled in doctoral programs in Australian universities while working in higher educational contexts in their own country. Data were collected from participant journals, an open questionnaire and dialogic email communications. The study…

14 CFR 151.95 - Fences; distance markers; navigational and landing aids; and offsite work.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Fences; distance markers; navigational and landing aids; and offsite work. 151.95 Section 151.95 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming...

[Objective evaluation of arterial intermittent claudication by the walking tolerance test. Comparative study of physiological walking and walking on a conveyor belt (author's transl)].

PubMed

Bouchet, J Y; Franco, A; Morzol, B; Beani, J C

1980-01-01

Two methods are used to evaluate the walking distance: physiological walking along a standard path (0% - 6 mk/h) and walking on a tread mill (10% - 3 km/h). In both tests, four data are checked: -- initial trouble distance, -- cramp or walking-distance, -- localisation of pain, -- recovery time. These tests are dependable for the diagnosis of arterial claudication, reproducible and well tolerated. Their results have been compared: there is no correlation between the initial trouble distance and the cramp distance. However there is a correlation between the cramp distance by physiological walking and on treadmill. Recovery time, if long, is a criteria of gravity. Interests of both methods are discussed.

New presentation method for magnetic resonance angiography images based on skeletonization

NASA Astrophysics Data System (ADS)

Nystroem, Ingela; Smedby, Orjan

2000-04-01

Magnetic resonance angiography (MRA) images are usually presented as maximum intensity projections (MIP), and the choice of viewing direction is then critical for the detection of stenoses. We propose a presentation method that uses skeletonization and distance transformations, which visualizes variations in vessel width independent of viewing direction. In the skeletonization, the object is reduced to a surface skeleton and further to a curve skeleton. The skeletal voxels are labeled with their distance to the original background. For the curve skeleton, the distance values correspond to the minimum radius of the object at that point, i.e., half the minimum diameter of the blood vessel at that level. The following image processing steps are performed: resampling to cubic voxels, segmentation of the blood vessels, skeletonization ,and reverse distance transformation on the curve skeleton. The reconstructed vessels may be visualized with any projection method. Preliminary results are shown. They indicate that locations of possible stenoses may be identified by presenting the vessels as a structure with the minimum radius at each point.

Geometric model of pseudo-distance measurement in satellite location systems

NASA Astrophysics Data System (ADS)

Panchuk, K. L.; Lyashkov, A. A.; Lyubchinov, E. V.

2018-04-01

The existing mathematical model of pseudo-distance measurement in satellite location systems does not provide a precise solution of the problem, but rather an approximate one. The existence of such inaccuracy, as well as bias in measurement of distance from satellite to receiver, results in inaccuracy level of several meters. Thereupon, relevance of refinement of the current mathematical model becomes obvious. The solution of the system of quadratic equations used in the current mathematical model is based on linearization. The objective of the paper is refinement of current mathematical model and derivation of analytical solution of the system of equations on its basis. In order to attain the objective, geometric analysis is performed; geometric interpretation of the equations is given. As a result, an equivalent system of equations, which allows analytical solution, is derived. An example of analytical solution implementation is presented. Application of analytical solution algorithm to the problem of pseudo-distance measurement in satellite location systems allows to improve the accuracy such measurements.

Distance Education in Southern Africa Conference, 1987. Papers 4.2: Professional Education and Practical Training at a Distance.

ERIC Educational Resources Information Center

Adey, David, Comp.; And Others

Fifteen papers from the University of South Africa's Conference on Distance Education are presented on professional education and practical training. They include: "The Art Work: From Concept to Realization" (Leon du Plessis and Koos van der Watt); "Distance Education for Industrial, Professional, and Practical Training" (Jacob…

Multi-objective decoupling algorithm for active distance control of intelligent hybrid electric vehicle

NASA Astrophysics Data System (ADS)

Luo, Yugong; Chen, Tao; Li, Keqiang

2015-12-01

The paper presents a novel active distance control strategy for intelligent hybrid electric vehicles (IHEV) with the purpose of guaranteeing an optimal performance in view of the driving functions, optimum safety, fuel economy and ride comfort. Considering the complexity of driving situations, the objects of safety and ride comfort are decoupled from that of fuel economy, and a hierarchical control architecture is adopted to improve the real-time performance and the adaptability. The hierarchical control structure consists of four layers: active distance control object determination, comprehensive driving and braking torque calculation, comprehensive torque distribution and torque coordination. The safety distance control and the emergency stop algorithms are designed to achieve the safety and ride comfort goals. The optimal rule-based energy management algorithm of the hybrid electric system is developed to improve the fuel economy. The torque coordination control strategy is proposed to regulate engine torque, motor torque and hydraulic braking torque to improve the ride comfort. This strategy is verified by simulation and experiment using a forward simulation platform and a prototype vehicle. The results show that the novel control strategy can achieve the integrated and coordinated control of its multiple subsystems, which guarantees top performance of the driving functions and optimum safety, fuel economy and ride comfort.

Spiral arms and massive star formation: Analysis of the CO face-on pictures of the galaxy

NASA Technical Reports Server (NTRS)

Clemens, D. P.; Sanders, D. B.; Scoville, N. Z.

1986-01-01

The face-on distribution of molecular gas in the first Galactic quadrant, derived from the Massachusetts-Stony Brook Galactic Plane CO Survey, was compared to the Galactic distribution of giant radio HII regions. The HII regions were found to preferentially select gas regions of higher than average density (more than twice the mean) and showed a strong correlation with the second power of the gas density. Systematic effects were tested with a Monte Carlo simulated HII region distribution and found to be negligible. The 135 HII regions were selected from the radio catalogs of Downes et at. (1980) and Wink et al. (1982). The HII regions were required to be within the CO survey 1 and b limits, within the solar circle, and not part of the 3 kpc expanding arm. The velocities of the HII regions were tabulated by the catalog authors and obvious associations with known objects and H2CO absorptions were used by them to assign distances. The distance assignments were here grouped into two categories; (1) those HII regions with definite distance assignments (85 objects); and (2) those HII regions with less secure distance assignments and those for which no near-far assignment was possible (50 objects).

The feasibility of using Microsoft Kinect v2 sensors during radiotherapy delivery.

PubMed

Edmunds, David M; Bashforth, Sophie E; Tahavori, Fatemeh; Wells, Kevin; Donovan, Ellen M

2016-11-08

Consumer-grade distance sensors, such as the Microsoft Kinect devices (v1 and v2), have been investigated for use as marker-free motion monitoring systems for radiotherapy. The radiotherapy delivery environment is challenging for such sen-sors because of the proximity to electromagnetic interference (EMI) from the pulse forming network which fires the magnetron and electron gun of a linear accelerator (linac) during radiation delivery, as well as the requirement to operate them from the control area. This work investigated whether using Kinect v2 sensors as motion monitors was feasible during radiation delivery. Three sensors were used each with a 12 m USB 3.0 active cable which replaced the supplied 3 m USB 3.0 cable. Distance output data from the Kinect v2 sensors was recorded under four condi-tions of linac operation: (i) powered up only, (ii) pulse forming network operating with no radiation, (iii) pulse repetition frequency varied between 6 Hz and 400 Hz, (iv) dose rate varied between 50 and 1450 monitor units (MU) per minute. A solid water block was used as an object and imaged when static, moved in a set of steps from 0.6 m to 2.0 m from the sensor and moving dynamically in two sinusoidal-like trajectories. Few additional image artifacts were observed and there was no impact on the tracking of the motion patterns (root mean squared accuracy of 1.4 and 1.1mm, respectively). The sensors' distance accuracy varied by 2.0 to 3.8 mm (1.2 to 1.4 mm post distance calibration) across the range measured; the precision was 1 mm. There was minimal effect from the EMI on the distance calibration data: 0 mm or 1 mm reported distance change (2 mm maximum change at one position). Kinect v2 sensors operated with 12 m USB 3.0 active cables appear robust to the radiotherapy treatment environment. © 2016 The Authors.

Spacetime Dynamics and Slow Neutrino Background

NASA Astrophysics Data System (ADS)

Zhang, Tianxi

2018-06-01

Space is a form of existence of matter, while time is a measure of change of the matter in the space. Issac Newton suggested that the space and time are absolute, not affected by matter and its motion. His first law of motion or the law of inertia says that, without net force acts on it, an object in motion remains the motion in a straight line at a constant speed. Ernest Mach proposed that the inertia of a body results from the gravitational interaction on the body by the rest of the entire universe. As mass is a measure of inertia, Mach’s principle can be simply stated as mass here is affected by matter there. On the basis of Mach’s principle, Albert Einstein considered the space and time to be relative and developed two theories of relativities. One called special relativity describes the effect of motion on spacetime and the other called general relativity describes the effect of matter on spacetime. Recently, the author has further considered reactions of the influenced spacetime on the moving objects, including photons. A moving object including a photon, because of its continuously keeping on displacement, disturbs the rest of the entire universe or distorts/curves the spacetime. The distorted or curved spacetime then generates an effective gravitational force to act back on the moving object or photon, so that reduces the object inertia or photon frequency. Considering the disturbance of spacetime by a photon is extremely weak, the author has modelled the effective gravitational force to be Newtonian and derived a new redshift-distance relation that not only perfectly explained the redshift-distance measurement of distant type Ia supernovae but also inherently obtained Hubble’s law as an approximate at small redshift. In this study, we will further analyse the reaction of the influenced spacetime on moving neutrinos and demonstrate the creation of slow neutrino (or tired neutrino) background that may be gravitationally orbiting around clusters, galaxies, and any celestial objects to play a role of dark mater in explaining the excess of galactic and clustery rotations. This work was supported by NSF/REU (Grant #: PHY-1559870) at Alabama A & M University.

Sonar beam dynamics in leaf-nosed bats

PubMed Central

Linnenschmidt, Meike; Wiegrebe, Lutz

2016-01-01

Ultrasonic emissions of bats are directional and delimit the echo-acoustic space. Directionality is quantified by the aperture of the sonar beam. Recent work has shown that bats often widen their sonar beam when approaching movable prey or sharpen their sonar beam when navigating through cluttered habitats. Here we report how nose-emitting bats, Phyllostomus discolor, adjust their sonar beam to object distance. First, we show that the height and width of the bats sonar beam, as imprinted on a parabolic 45 channel microphone array, varies even within each animal and this variation is unrelated to changes in call level or spectral content. Second, we show that these animals are able to systematically decrease height and width of their sonar beam while focusing on the approaching object. Thus it appears that sonar beam sharpening is a further, facultative means of reducing search volume, likely to be employed by stationary animals when the object position is close and unambiguous. As only half of our individuals sharpened their beam onto the approaching object we suggest that this strategy is facultative, under voluntary control, and that beam formation is likely mediated by muscular control of the acoustic aperture of the bats’ nose leaf. PMID:27384865

Sonar beam dynamics in leaf-nosed bats.

PubMed

Linnenschmidt, Meike; Wiegrebe, Lutz

2016-07-07

Ultrasonic emissions of bats are directional and delimit the echo-acoustic space. Directionality is quantified by the aperture of the sonar beam. Recent work has shown that bats often widen their sonar beam when approaching movable prey or sharpen their sonar beam when navigating through cluttered habitats. Here we report how nose-emitting bats, Phyllostomus discolor, adjust their sonar beam to object distance. First, we show that the height and width of the bats sonar beam, as imprinted on a parabolic 45 channel microphone array, varies even within each animal and this variation is unrelated to changes in call level or spectral content. Second, we show that these animals are able to systematically decrease height and width of their sonar beam while focusing on the approaching object. Thus it appears that sonar beam sharpening is a further, facultative means of reducing search volume, likely to be employed by stationary animals when the object position is close and unambiguous. As only half of our individuals sharpened their beam onto the approaching object we suggest that this strategy is facultative, under voluntary control, and that beam formation is likely mediated by muscular control of the acoustic aperture of the bats' nose leaf.

Language within your reach: near-far perceptual space and spatial demonstratives.

PubMed

Coventry, Kenny R; Valdés, Berenice; Castillo, Alejandro; Guijarro-Fuentes, Pedro

2008-09-01

Spatial demonstratives (this/that) play a crucial role when indicating object locations using language. However, the relationship between the use of these proximal and distal linguistic descriptors and the near (peri-personal) versus far (extra-personal) perceptual space distinction is a source of controversy [Kemmerer, D. (1999). "Near" and "far" in language and perception. Cognition 73, 35-63], and has been hitherto under investigated. Two experiments examined the influence of object distance from speaker, tool use (participants pointed at objects with their finger/arm or with a stick), and interaction with objects (whether or not participants placed objects themselves) on spatial demonstrative use (e.g. this/that red triangle) in English (this/that) and Spanish (este/ese/aquel). The results show that the use of demonstratives across two languages is affected by distance from speaker and by both tool use and interaction with objects. These results support the view that spatial demonstrative use corresponds with a basic distinction between near and far perceptual space.

Tonic accommodation predicts closed-loop accommodation responses.

PubMed

Liu, Chunming; Drew, Stefanie A; Borsting, Eric; Escobar, Amy; Stark, Lawrence; Chase, Christopher

2016-12-01

The purpose of this study is to examine the potential relationship between tonic accommodation (TA), near work induced TA-adaptation and the steady state closed-loop accommodation response (AR). Forty-two graduate students participated in the study. Various aspects of their accommodation system were objectively measured using an open-field infrared auto-refractor (Grand Seiko WAM-5500). Tonic accommodation was assessed in a completely dark environment. The association between TA and closed-loop AR was assessed using linear regression correlations and t-test comparisons. Initial mean baseline TA was 1.84diopter (D) (SD±1.29D) with a wide distribution range (-0.43D to 5.14D). For monocular visual tasks, baseline TA was significantly correlated with the closed-loop AR. The slope of the best fit line indicated that closed-loop AR varied by approximately 0.3D for every 1D change in TA. This ratio was consistent across a variety of viewing distances and different near work tasks, including both static targets and continuous reading. Binocular reading conditions weakened the correlation between baseline TA and AR, although results remained statistically significant. The 10min near reading task with a 3D demand did not reveal significant near work induced TA-adaptation for either monocular or binocular conditions. Consistently, the TA-adaptation did not show any correlation with AR during reading. This study found a strong association between open-loop TA and closed-loop AR across a variety of viewing distances and different near work tasks. Difference between the correlations under monocular and binocular reading condition suggests a potential role for vergence compensation during binocular closed-loop AR. Copyright © 2016 Elsevier Ltd. All rights reserved.

How bright planets became dim stars: planetary speculations in John Herschel's double star astronomy

NASA Astrophysics Data System (ADS)

Case, S.

2014-03-01

Previous research on the origins of double star astronomy in the early nineteenth century emphasized the role mathematical methods and instrumentation played in motivating early observations of these objects. The work of the British astronomer John Herschel, however, shows that questions regarding the physical nature of double stars were also important. In particular, an analysis of John Herschel's early work on double stars illustrates the way in which speculations regarding these objects were shaped by assumptions of the properties of stars themselves. For Herschel, a major consideration in double star astronomy was distinguishing between types of double stars. Optical doubles were useful in determining parallax while binary doubles were not. In practice, classification of a specific double star pair into one of these categories was based on the assumption that stars were of approximately the same luminosity and thus differences in relative brightness between stars were caused by difference in distances. Such assumptions, though ultimately abandoned, would lead Herschel in the 1830s to advance the possibility that the dim companion stars in certain double star pairs were not stars at all but in fact planets.

How bright planets became dim stars: planetary speculations in John Herschel's double star astronomy.

PubMed

Case, Stephen

2014-03-01

Previous research on the origins of double star astronomy in the early nineteenth century emphasized the role mathematical methods and instrumentation played in motivating early observations of these objects. The work of the British astronomer John Herschel, however, shows that questions regarding the physical nature of double stars were also important. In particular, an analysis of John Herschel's early work on double stars illustrates the way in which speculations regarding these objects were shaped by assumptions of the properties of stars themselves. For Herschel, a major consideration in double star astronomy was distinguishing between types of double stars. Optical doubles were useful in determining parallax while binary doubles were not. In practice, classification of a specific double star pair into one of these categories was based on the assumption that stars were of approximately the same luminosity and thus differences in relative brightness between stars were caused by difference in distances. Such assumptions, though ultimately abandoned, would lead Herschel in the 1830s to advance the possibility that the dim companion stars in certain double star pairs were not stars at all but in fact planets. Copyright © 2014 Elsevier Ltd. All rights reserved.

Propagation and Detection of Neutrinos from Distant Objects

NASA Astrophysics Data System (ADS)

Bottino, A.; Kim, C. W.; Kim, Jewan; Lam, W. P.

We discuss how an initial composition of wave packets representing the neutrinos, emitted by distant objects such as supernovae, is modified as the neutrinos travel a long distance to the earth and how these modifications affect the detection of such neutrinos. In particular, observed neutrino masses are shown to depend on the mass square difference of the i-th and j-th flavors i.e., mi2 - mj2, L (the distance traveled), and a resolution time of the detector as well as on how neutrinos emerge from the star.

Depth perception

NASA Astrophysics Data System (ADS)

Sirola, Christopher

2017-03-01

In most disciplines, finding the distance from one object to the next is, at least in theory, a simple operation. Not so in astronomy. While the size of Earth itself was determined with a fair degree of accuracy in ancient times, the scale of the solar system wasn't fully understood until just a few centuries ago, and the distances to even the closest of stars wasn't reliably determined until Friedrich Bessel measured the distance to 61 Cygni in 1838.

Socio-demographic, personal, environmental and behavioral correlates of different modes of transportation to work among Norwegian parents.

PubMed

Bjørkelund, Oline Anita; Degerud, Hanna; Bere, Elling

2016-01-01

Cycling and brisk-walking to work represents an opportunity to incorporate sustainable transport related moderate- to- vigorous physical activity (MVPA) into daily routine among adults, and thus, may make an important contributing to health. Despite the fact that walking and cycling is an option for many commuters and also brings a number of benefits, a considerable proportion of commuters choose to use other means of transport when cycling and walking would be a highly appropriate transport mode. The object of this study was to assess the associations between modes of commuting to the workplace among parental adults; taking socio-demographic, personal, environmental and behavioral factors into account. Data from a cross- sectional questionnaire were collected from a sample of 709 parents (23 % men and 77 % women) of children aged 10-12 years-old in two Norwegian counties, Hedmark and Telemark. Commuting behavior, socio- demographic determinants, personal and environmental factors were ascertained using questionnaire data from the Fruit and Vegetables Makes the Marks project (FVMM). Multivariate logistic regressions were applied. In total, 70 % of adults were categorized as car commuters to and from work, 12 % was categorized as a cyclist and 7 % as a walker. The multivariate analyses showed that active commuters were more likely to have a shorter distance to work and perceived the traffic as more safe. Moreover, those who actively commute to the workplace considered commuting as a way to obtain health benefits and a way to reduce CO 2 emissions. Active commuters also considered weather to be an obstacle to active commuting. In this cross-sectional study of parents living in sub-urban Norway, we found that active commuting to and from the workplace were associated with a shorter distance to work, traffic safety, environmental concern, health benefits and weather condition. In light of these findings, cycling to work seems to be the most appropriate target for interventions and public health campaigns within this population.

Passive method of eliminating accommodation/convergence disparity in stereoscopic head-mounted displays

NASA Astrophysics Data System (ADS)

Eichenlaub, Jesse B.

2005-03-01

The difference in accommodation and convergence distance experienced when viewing stereoscopic displays has long been recognized as a source of visual discomfort. It is especially problematic in head mounted virtual reality and enhanced reality displays, where images must often be displayed across a large depth range or superimposed on real objects. DTI has demonstrated a novel method of creating stereoscopic images in which the focus and fixation distances are closely matched for all parts of the scene from close distances to infinity. The method is passive in the sense that it does not rely on eye tracking, moving parts, variable focus optics, vibrating optics, or feedback loops. The method uses a rapidly changing illumination pattern in combination with a high speed microdisplay to create cones of light that converge at different distances to form the voxels of a high resolution space filling image. A bench model display was built and a series of visual tests were performed in order to demonstrate the concept and investigate both its capabilities and limitations. Results proved conclusively that real optical images were being formed and that observers had to change their focus to read text or see objects at different distances

Phase Imaging using Focusing Polycapillary Optics

NASA Astrophysics Data System (ADS)

Bashir, Sajid

The interaction of X rays in diagnostic energy range with soft tissues can be described by Compton scattering and by the complex refractive index, which together characterize the attenuation properties of the tissue and the phase imparted to X rays passing through it. Many soft tissues exhibit extremely similar attenuation, so that their discrimination using conventional radiography, which generates contrast in an image through differential attenuation, is challenging. However, these tissues will impart phase differences significantly greater than attenuation differences to the X rays passing through them, so that phase-contrast imaging techniques can enable their discrimination. A major limitation to the widespread adoption of phase-contrast techniques is that phase contrast requires significant spatial coherence of the X-ray beam, which in turn requires specialized sources. For tabletop sources, this often requires a small (usually in the range of 10-50 micron) X-ray source. In this work, polycapillary optics were employed to create a small secondary source from a large spot rotating anode. Polycapillary optics consist of arrays of small hollow glass tubes through which X rays can be guided by total internal reflection from the tube walls. By tapering the tubes to guide the X rays to a point, they can be focused to a small spot which can be used as a secondary source. The polycapillary optic was first aligned with the X-ray source. The spot size was measured using a computed radiography image plate. Images were taken at a variety of optic-to-object and object-to-detector distances and phase-contrast edge enhancement was observed. Conventional absorption images were also acquired at a small object-to detector distances for comparison. Background division was performed to remove strong non-uniformity due to the optics. Differential phase contrast reconstruction demonstrates promising preliminary results. This manuscript is divided into six chapters. The second chapter describes the limitations of conventional imaging methods and benefits of the phase imaging. Chapter three covers different types of X-ray photon interactions with matter. Chapter four describes the experimental set-up and different types of images acquired along with their analysis. Chapter five summarizes the findings in this project and describes future work as well.

Design of apochromatic lens with large field and high definition for machine vision.

PubMed

Yang, Ao; Gao, Xingyu; Li, Mingfeng

2016-08-01

Precise machine vision detection for a large object at a finite working distance (WD) requires that the lens has a high resolution for a large field of view (FOV). In this case, the effect of a secondary spectrum on image quality is not negligible. According to the detection requirements, a high resolution apochromatic objective is designed and analyzed. The initial optical structure (IOS) is combined with three segments. Next, the secondary spectrum of the IOS is corrected by replacing glasses using the dispersion vector analysis method based on the Buchdahl dispersion equation. Other aberrations are optimized by the commercial optical design software ZEMAX by properly choosing the optimization function operands. The optimized optical structure (OOS) has an f-number (F/#) of 3.08, a FOV of φ60  mm, a WD of 240 mm, and a modulated transfer function (MTF) of all fields of more than 0.1 at 320  cycles/mm. The design requirements for a nonfluorite material apochromatic objective lens with a large field and high definition for machine vision detection have been achieved.

Control of aperture closure initiation during reach-to-grasp movements under manipulations of visual feedback and trunk involvement in Parkinson's disease.

PubMed

Rand, Miya Kato; Lemay, Martin; Squire, Linda M; Shimansky, Yury P; Stelmach, George E

2010-03-01

The present project was aimed at investigating how two distinct and important difficulties (coordination difficulty and pronounced dependency on visual feedback) in Parkinson's disease (PD) affect each other for the coordination between hand transport toward an object and the initiation of finger closure during reach-to-grasp movement. Subjects with PD and age-matched healthy subjects made reach-to-grasp movements to a dowel under conditions in which the target object and/or the hand were either visible or not visible. The involvement of the trunk in task performance was manipulated by positioning the target object within or beyond the participant's outstretched arm to evaluate the effects of increasing the complexity of intersegmental coordination under different conditions related to the availability of visual feedback in subjects with PD. General kinematic characteristics of the reach-to-grasp movements of the subjects with PD were altered substantially by the removal of target object visibility. Compared with the controls, the subjects with PD considerably lengthened transport time, especially during the aperture closure period, and decreased peak velocity of wrist and trunk movement without target object visibility. Most of these differences were accentuated when the trunk was involved. In contrast, these kinematic parameters did not change depending on the visibility of the hand for both groups. The transport-aperture coordination was assessed in terms of the control law according to which the initiation of aperture closure during the reach occurred when the hand distance-to-target crossed a hand-target distance threshold for grasp initiation that is a function of peak aperture, hand velocity and acceleration, trunk velocity and acceleration, and trunk-target distance at the time of aperture closure initiation. When the hand or the target object was not visible, both groups increased the hand-target distance threshold for grasp initiation compared to its value under full visibility, implying an increase in the hand-target distance-related safety margin for grasping. The increase in the safety margin due to the absence of target object vision or the absence of hand vision was accentuated in the subjects with PD compared to that in the controls. The pronounced increase in the safety margin due to absence of target object vision for the subjects with PD was further accentuated when the trunk was involved compared to when it was not involved. The results imply that individuals with PD have significant limitations regarding neural computations required for efficient utilization of internal representations of target object location and hand motion as well as proprioceptive information about the hand to compensate for the lack of visual information during the performance of complex multisegment movements.

Distance Education and Organizational Environment

ERIC Educational Resources Information Center

East, Jean F.; LaMendola, Walter; Alter, Catherine

2014-01-01

As distance education models in social work education continue to grow, this study addresses prevalence and type of models in graduate social work programs and the perceptions of deans about the future of e-learning models of curriculum delivery. The study was an exploratory sequential mixed-methods design including a national survey of 121…

Implications for Academic Workload of the Changing Role of Distance Educators

ERIC Educational Resources Information Center

Bezuidenhout, Adéle

2015-01-01

The changing work roles and resulting workloads of distance educators hold significant implications for the wellbeing and mental health of academics. New work roles include redesigning curricula for online delivery, increasing staff-student ratios and demands for student-support, management of part-time staff, and 24-h availability. This research…

Pedagogical Implications of Working with Doctoral Students at a Distance

ERIC Educational Resources Information Center

Wikeley, Felicity; Muschamp, Yolande

2004-01-01

This paper discusses the issues raised when delivering professional doctorate programmes to students at a distance. It explores the importance in doctoral study of engagement with a research community, what a "community of practice" might mean within the academic context and the problematic nature of working with students already operating within…

Integrating Web Conferencing and Field Work for Preparing Rural Special Educators.

ERIC Educational Resources Information Center

Chapman, Carrie; Knapczyk, Dennis

Distance learning can be a useful approach for preparing teachers who are mid-career changers or who are working on limited licenses, especially in rural areas. At Indiana University, the Collaborative Teacher Education Program uses multiple distance education technologies to provide special education teacher preparation in mild (high-incidence)…

Cosmic distance duality and cosmic transparency

NASA Astrophysics Data System (ADS)

Nair, Remya; Jhingan, Sanjay; Jain, Deepak

2012-12-01

We compare distance measurements obtained from two distance indicators, Supernovae observations (standard candles) and Baryon acoustic oscillation data (standard rulers). The Union2 sample of supernovae with BAO data from SDSS, 6dFGS and the latest BOSS and WiggleZ surveys is used in search for deviations from the distance duality relation. We find that the supernovae are brighter than expected from BAO measurements. The luminosity distances tend to be smaller then expected from angular diameter distance estimates as also found in earlier works on distance duality, but the trend is not statistically significant. This further constrains the cosmic transparency.

25 CFR 169.9 - Connection with natural objects.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Connection with natural objects. 169.9 Section 169.9... LANDS § 169.9 Connection with natural objects. When the distance to an established corner of the public survey is more than 6 miles, this connection will be made with a natural object or a permanent monument...

25 CFR 169.9 - Connection with natural objects.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 25 Indians 1 2011-04-01 2011-04-01 false Connection with natural objects. 169.9 Section 169.9... LANDS § 169.9 Connection with natural objects. When the distance to an established corner of the public survey is more than 6 miles, this connection will be made with a natural object or a permanent monument...

Reproducing 2D breast mammography images with 3D printed phantoms

NASA Astrophysics Data System (ADS)

Clark, Matthew; Ghammraoui, Bahaa; Badal, Andreu

2016-03-01

Mammography is currently the standard imaging modality used to screen women for breast abnormalities and, as a result, it is a tool of great importance for the early detection of breast cancer. Physical phantoms are commonly used as surrogates of breast tissue to evaluate some aspects of the performance of mammography systems. However, most phantoms do not reproduce the anatomic heterogeneity of real breasts. New fabrication technologies, such as 3D printing, have created the opportunity to build more complex, anatomically realistic breast phantoms that could potentially assist in the evaluation of mammography systems. The primary objective of this work is to present a simple, easily reproducible methodology to design and print 3D objects that replicate the attenuation profile observed in real 2D mammograms. The secondary objective is to evaluate the capabilities and limitations of the competing 3D printing technologies, and characterize the x-ray properties of the different materials they use. Printable phantoms can be created using the open-source code introduced in this work, which processes a raw mammography image to estimate the amount of x-ray attenuation at each pixel, and outputs a triangle mesh object that encodes the observed attenuation map. The conversion from the observed pixel gray value to a column of printed material with equivalent attenuation requires certain assumptions and knowledge of multiple imaging system parameters, such as x-ray energy spectrum, source-to-object distance, compressed breast thickness, and average breast material attenuation. A detailed description of the new software, a characterization of the printed materials using x-ray spectroscopy, and an evaluation of the realism of the sample printed phantoms are presented.

High-Sensitivity Measurement of Density by Magnetic Levitation.

PubMed

Nemiroski, Alex; Kumar, A A; Soh, Siowling; Harburg, Daniel V; Yu, Hai-Dong; Whitesides, George M

2016-03-01

This paper presents methods that use Magnetic Levitation (MagLev) to measure very small differences in density of solid diamagnetic objects suspended in a paramagnetic medium. Previous work in this field has shown that, while it is a convenient method, standard MagLev (i.e., where the direction of magnetization and gravitational force are parallel) cannot resolve differences in density <10(-4) g/cm(3) for macroscopic objects (>mm) because (i) objects close in density prevent each other from reaching an equilibrium height due to hard contact and excluded volume, and (ii) using weaker magnets or reducing the magnetic susceptibility of the medium destabilizes the magnetic trap. The present work investigates the use of weak magnetic gradients parallel to the faces of the magnets as a means of increasing the sensitivity of MagLev without destabilization. Configuring the MagLev device in a rotated state (i.e., where the direction of magnetization and gravitational force are perpendicular) relative to the standard configuration enables simple measurements along the axes with the highest sensitivity to changes in density. Manipulating the distance of separation between the magnets or the lengths of the magnets (along the axis of measurement) enables the sensitivity to be tuned. These modifications enable an improvement in the resolution up to 100-fold over the standard configuration, and measurements with resolution down to 10(-6) g/cm(3). Three examples of characterizing the small differences in density among samples of materials having ostensibly indistinguishable densities-Nylon spheres, PMMA spheres, and drug spheres-demonstrate the applicability of rotated Maglev to measuring the density of small (0.1-1 mm) objects with high sensitivity. This capability will be useful in materials science, separations, and quality control of manufactured objects.

Facilitating a teleconference-delivered fatigue management program: perspectives of occupational therapists.

PubMed

Dunleavy, Leah; Preissner, Katharine L; Finlayson, Marcia L

2013-12-01

Telehealth refers to the provision of health information and services across a geographical distance. Little is known about the experiences of occupational therapists using this method of service delivery. The study explored the process of facilitating a telehealth intervention from the perspective of occupational therapists. Occupational therapists completed SOAP (Subjective, Objective, Assessment, and Plan) notes after facilitating group-based, teleconference-delivered fatigue management groups to people with multiple sclerosis. Notes were also documented after therapist team meetings. All SOAP notes and field notes were subjected to thematic analysis. Five major themes were identified. "Managing time" was the central theme and was facilitated by professional foundation and challenged by logistics. Managing time contributed to challenging work, which led to the realization that it can work! Based on study findings, the theory and research on clinical reasoning, professional development, and adult learning are relevant to developing curricula that prepare occupational therapists for using telehealth approaches in practice.

Nano-viscosity of supercooled liquid measured by fluorescence correlation spectroscopy: Pressure and temperature dependence and the density scaling

NASA Astrophysics Data System (ADS)

Meier, G.; Gapinski, J.; Ratajczyk, M.; Lettinga, M. P.; Hirtz, K.; Banachowicz, E.; Patkowski, A.

2018-03-01

The Stokes-Einstein relation allows us to calculate apparent viscosity experienced by tracers in complex media on the basis of measured self-diffusion coefficients. Such defined nano-viscosity values can be obtained through single particle techniques, like fluorescence correlation spectroscopy (FCS) and particle tracking (PT). In order to perform such measurements, as functions of pressure and temperature, a new sample cell was designed and is described in this work. We show that this cell in combination with a long working distance objective of the confocal microscope can be used for successful FCS, PT, and confocal imaging experiments in broad pressure (0.1-100 MPa) and temperature ranges. The temperature and pressure dependent nano-viscosity of a van der Waals liquid obtained from the translational diffusion coefficient measured in this cell by means of FCS obeys the same scaling as the rotational relaxation and macro-viscosity of the system.

Kinematics of prehension and pointing movements in C6 quadriplegic patients.

PubMed

Laffont, I; Briand, E; Dizien, O; Combeaud, M; Bussel, B; Revol, M; Roby-Brami, A

2000-06-01

C6 quadriplegic patients lack voluntary control of their triceps muscle but can still perform reaching movements to grasp objects or point to targets. The present study documents the kinematic properties of reaching in these patients. We investigated the kinematics of prehension and pointing movements in four quadriplegic patients and five control subjects. Prehension and pointing movements were recorded for each subject using various object positions (ie different directions and distances from the subject). The 3D motion was analyzed with Fastrack Polhemus sensors. During prehension tasks the velocity profile of control subjects showed two peaks (go and return); the first velocity peak was scaled to the distance of the object. In quadriplegic patients there was a third intermediary peak corresponding to the grasping of the object. The amplitude of the first peak was slightly smaller than in control subjects. Velocity was scaled to the distance of the object, but with a greater dispersion than in control subjects. Total movement time was longer in quadriplegics because of the prolonged grasping phase. There were few differences in the pointing movements of normal and quadriplegic subjects. The scapula contributed more to the reaching phase of both movements in quadriplegic patients. In spite of some quantitative differences, the kinematics of the hand during reaching and pointing in quadriplegic patients are surprisingly similar to those of control subjects. Spinal Cord (2000) 38, 354 - 362.

Improved Iris Recognition through Fusion of Hamming Distance and Fragile Bit Distance.

PubMed

Hollingsworth, Karen P; Bowyer, Kevin W; Flynn, Patrick J

2011-12-01

The most common iris biometric algorithm represents the texture of an iris using a binary iris code. Not all bits in an iris code are equally consistent. A bit is deemed fragile if its value changes across iris codes created from different images of the same iris. Previous research has shown that iris recognition performance can be improved by masking these fragile bits. Rather than ignoring fragile bits completely, we consider what beneficial information can be obtained from the fragile bits. We find that the locations of fragile bits tend to be consistent across different iris codes of the same eye. We present a metric, called the fragile bit distance, which quantitatively measures the coincidence of the fragile bit patterns in two iris codes. We find that score fusion of fragile bit distance and Hamming distance works better for recognition than Hamming distance alone. To our knowledge, this is the first and only work to use the coincidence of fragile bit locations to improve the accuracy of matches.

A new method to quantify liner deformation within a prosthetic socket for below knee amputees.

PubMed

Lenz, Amy L; Johnson, Katie A; Bush, Tamara Reid

2018-06-06

Many amputees who wear a leg prosthesis develop significant skin wounds on their residual limb. The exact cause of these wounds is unclear as little work has studied the interface between the prosthetic device and user. Our research objective was to develop a quantitative method for assessing displacement patterns of the gel liner during walking for patients with transtibial amputation. Using a reflective marker system and a custom clear socket, evaluations were conducted with a clear transparent test socket mounted over a plaster limb model and a deformable limb model. Distances between markers placed on the limb were measured with a digital caliper and then compared with data from the motion capture system. Additionally, the rigid plaster set-up was moved in the capture volume to simulate walking and evaluate if inter-marker distances changed in comparison to static data. Dynamic displacement trials were then collected to measure changes in inter-marker distance due to vertical elongation of the gel liner. Static and dynamic inter-marker distances within day and across days confirmed the ability to accurately capture displacements using this new approach. These results encourage this novel method to be applied to a sample of amputee patients during walking to assess displacements and the distribution of the liner deformation within the socket. The ability to capture changes in deformation of the gel liner will provide new data that will enable clinicians and researchers to improve design and fit of the prosthesis so the incidence of pressure ulcers can be reduced. Copyright © 2018 Elsevier Ltd. All rights reserved.

Introital ultrasonography: a comparison of women with stress incontinence due to urethral hypermobility and continent women.

PubMed

Cassadó, Jordi; Pessarrodona, Antoni; Tulleuda, Raquel; Cabero, Lluís; Valls, Marta; Quintana, Salvador; Rodríguez-Carballeira, Mónica

2006-10-01

To determine if there is a variable on introital ultrasonography (IUS) that can be used to distinguish between women with stress urinary incontinence (SUI) due to urethral hypermobility (UH) and continent women. This single-centre, prospective, blind, cohort, observational study comprised 383 women (245 continent and 138 incontinent) who were all appropriately informed volunteers selected according to the inclusion criteria. IUS with a convex probe was performed on all women; the measurement plane was standardized and coordinates were obtained at rest and on straining. Several distances were measured to determine if any provided an objective distinction between continent and incontinent women. Among all the IUS variables assessed, sliding (calculated as the difference between the distance urethra-bladder neck, U-BN, at rest and under stress) was the best for distinguishing continent and incontinent women. The receiver operating characteristic curves showed that with a threshold of 8 mm, sliding had a sensitivity of 92% and a specificity of 79.6% for detecting SUI due to UH. The distances symphysis-urethra (S-U) and U-BN at rest could also discriminate, but with lower significance. IUS is an important tool for diagnosing SUI; there are three independent variables, one dynamic (sliding) and two static (distances S-U and U-BN), that can be used to distinguish between continent women and those with SUI due to UH. Sliding is the most reliable, as it has the highest sensitivity and specificity. We think that the simplicity, low financial cost and reliability of IUS could allow it to be a routine procedure for physicians working in incontinence units.

36 CFR 14.25 - Documents which must accompany application.

Code of Federal Regulations, 2010 CFR

2010-07-01

... terminal points of the survey should be accurately connected by course and distance to the nearest corner... connection will be made to some prominent natural object or permanent monument, which can be readily... the witness monuments and the connecting courses and distances to the original corners should be shown...

Vergence, Vision, and Geometric Optics

ERIC Educational Resources Information Center

Keating, Michael P.

1975-01-01

Provides a definition of vergence in terms of the curvature of the wave fronts, and gives examples to illustrate the advantages of this approach. The vergence treatment of geometrical optics provides both conceptual and algebraic advantages, particularly for the life science student, over the traditional object distance-image distance-focal length…

Managing Distance Education Institutions through Value Chain Analysis: the Nigerian Experience.

ERIC Educational Resources Information Center

Aderinto, J. A.; Akintayo, M. O.

Value chain analysis can gauge, analyze, and predict organization effects to control cost in light of achieving strategic organization objectives of distance education. Value chain analysis enables organizations to accomplish their goal or mission through cost effectiveness or differentiation. The value chain activity structure in a distance…

Some Instructional Strategies for Improving Learning from Distance Teaching Materials.

ERIC Educational Resources Information Center

Marland, P. W.; Store, R. E.

1982-01-01

Examines some traditional instructional strategies used to improve textual materials for learning at a distance, including advance organizers, overviews, pretests, objectives, and inserted questions, together with devices in typography and graphics. Research in each area is reviewed and guidelines are given for using each strategy. An extensive…

Study into Point Cloud Geometric Rigidity and Accuracy of TLS-Based Identification of Geometric Bodies

NASA Astrophysics Data System (ADS)

Klapa, Przemyslaw; Mitka, Bartosz; Zygmunt, Mariusz

2017-12-01

Capability of obtaining a multimillion point cloud in a very short time has made the Terrestrial Laser Scanning (TLS) a widely used tool in many fields of science and technology. The TLS accuracy matches traditional devices used in land surveying (tacheometry, GNSS - RTK), but like any measurement it is burdened with error which affects the precise identification of objects based on their image in the form of a point cloud. The point’s coordinates are determined indirectly by means of measuring the angles and calculating the time of travel of the electromagnetic wave. Each such component has a measurement error which is translated into the final result. The XYZ coordinates of a measuring point are determined with some uncertainty and the very accuracy of determining these coordinates is reduced as the distance to the instrument increases. The paper presents the results of examination of geometrical stability of a point cloud obtained by means terrestrial laser scanner and accuracy evaluation of solids determined using the cloud. Leica P40 scanner and two different settings of measuring points were used in the tests. The first concept involved placing a few balls in the field and then scanning them from various sides at similar distances. The second part of measurement involved placing balls and scanning them a few times from one side but at varying distances from the instrument to the object. Each measurement encompassed a scan of the object with automatic determination of its position and geometry. The desk studies involved a semiautomatic fitting of solids and measurement of their geometrical elements, and comparison of parameters that determine their geometry and location in space. The differences of measures of geometrical elements of balls and translations vectors of the solids centres indicate the geometrical changes of the point cloud depending on the scanning distance and parameters. The results indicate the changes in the geometry of scanned objects depending on the point cloud quality and distance from the measuring instrument. Varying geometrical dimensions of the same element suggest also that the point cloud does not keep a stable geometry of measured objects.

Size illusion, distance illusion, and terrestrial passage: comment on reed.

PubMed

Loftus, G R

1985-03-01

Two assumptions of Reed's (1984) terrestrial passage theory are questioned. First, Reed assumes that the moon's failure to increase in visual subtense while elevating is accounted for strictly by perceptual distancing. This allows a formal account of the moon distance illusion, but at the expense of a compelling explanation of the moon size illusion. Second, in order to explain the distance illusion, Reed assumes that all objects, regardless of their perceived altitude, are perceived to start from a common point at the horizon. Several alternative application of Reed's terrestrial-passage foundation to the actual illusions are suggested.

Evaluation of a distance-learning immunology and pathology module in a postgraduate biomedical science course.

PubMed

Ryan, M T; Mulholland, C W

2005-01-01

An electronic presentation of materials for a distance-learning immunology and pathology module from a postgraduate biomedical science course is evaluated. Two different electronic presentation formats for the delivery of the educational material to distance learners are assessed. Responses from users of this material highlighted a preference for a format that has a design tailored to distance learning. There was no significant difference in learning outcome between those taking the module on campus and by distance learning. This suggests that the prerequisites for entry, learning materials and direction given to the students studying by distance learning are adequate for these students to achieve the learning objectives outlined in the course. The evaluation also gave direction for areas within the (CAL) application that can be improved for future students.

Small or far away? Size and distance perception in the praying mantis

PubMed Central

Bissianna, Geoffrey

2016-01-01

Stereo or ‘3D’ vision is an important but costly process seen in several evolutionarily distinct lineages including primates, birds and insects. Many selective advantages could have led to the evolution of stereo vision, including range finding, camouflage breaking and estimation of object size. In this paper, we investigate the possibility that stereo vision enables praying mantises to estimate the size of prey by using a combination of disparity cues and angular size cues. We used a recently developed insect 3D cinema paradigm to present mantises with virtual prey having differing disparity and angular size cues. We predicted that if they were able to use these cues to gauge the absolute size of objects, we should see evidence for size constancy where they would strike preferentially at prey of a particular physical size, across a range of simulated distances. We found that mantises struck most often when disparity cues implied a prey distance of 2.5 cm; increasing the implied distance caused a significant reduction in the number of strikes. We, however, found no evidence for size constancy. There was a significant interaction effect of the simulated distance and angular size on the number of strikes made by the mantis but this was not in the direction predicted by size constancy. This indicates that mantises do not use their stereo vision to estimate object size. We conclude that other selective advantages, not size constancy, have driven the evolution of stereo vision in the praying mantis. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269605